Update self hosted instructions

README.md

@@ -69,7 +69,7 @@ jobs:
         run: python -c "import sys; print(sys.version)"
 ```
 
-Download and setup a version of Python that does not come pre-installed on an image:
+Download and set up a version of Python that does not come preinstalled on an image:
 ```yaml
 jobs:
   build:
@@ -97,6 +97,7 @@ Check out our detailed guide on using [Python with GitHub Actions](https://help.
     - For detailed information regarding the available versions of Python that are installed see [Software installed on GitHub-hosted runners](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/software-installed-on-github-hosted-runners)
     - For every minor version of Python, expect only the latest patch to be preinstalled. See [Semantic Versioning](https://semver.org/) for more information
     - If `3.8.1` is installed for example, and `3.8.2` is released, expect `3.8.1` to be removed and replaced by `3.8.2` in the tools cache
+    - If the exact patch version doesn't matter to you, specifying just the major and minor version will get you the latest preinstalled patch version. In this case, for example, the version spec 3.8 will use the 3.8.2 found in the cache
 - Downloadable Python versions from GitHub Releases ([actions/python-versions](https://github.com/actions/python-versions/releases))
     - All available versions are listed in the [version-manifest.json](https://github.com/actions/python-versions/blob/master/versions-manifest.json) file
     - If there is a specific version of Python that is not available, you can open an issue in the `python-versions` repository 
@@ -117,29 +118,13 @@ GitHub virtual environments are setup in [actions/virtual-environments](https://
 
 # Using `setup-python` with a self hosted runner
 
-If you would like to use `setup-python` and a self-hosted runner, you have two options
-  - Setup a tools cache locally and download all the versions of Python & PyPy that you would like once
-      - Takes a little bit to time to initially setup
-      - This will be the most stable and fastest option long-term as it will require no extra downloads every-time there is a run
-  - Download and setup a version of python every-time
-      - Requires no extra setup (good if you want to quickly get up and running, discouraged for long term use)
-      - `setup-python` will take a little longer to run
-      - Note: when downloading versions of Python for Windows, an MSI installer is used which can modify some registry settings
+If you would like to use `setup-python` and a self-hosted runner, there isn't much that you need to do. When `setup-python` is run for the first time with a version of Python that it doesn't have, it will download the appropriate version, and setup the tools cache on your machine. Any subsequent runs will use the python versions that were previously downloaded.
 
-### Setting up a local tools cache
-
-- Create an global environment variable called `AGENT_TOOLSDIRECTORY` that will point to the root directory of where you want the tools installed. The env variable is preferably global as it must be set in the shell that will install the tools cache, along with the shell that the runner will be using.
-    - This env variable is used internally by the runner to set the `RUNNER_TOOL_CACHE` env variable
-    - Example for Administrator Powershell: `[System.Environment]::SetEnvironmentVariable("AGENT_TOOLSDIRECTORY", "C:\hostedtoolcache\windows", [System.EnvironmentVariableTarget]::Machine)` (restart the shell afterwards)
--  Download the appropriate NPM packages from the [GitHub Actions NPM registry](https://github.com/orgs/actions/packages)
-    - Make sure to have `npm` installed, and then [configure npm for use with GitHub packages](https://help.github.com/en/packages/using-github-packages-with-your-projects-ecosystem/configuring-npm-for-use-with-github-packages#authenticating-to-github-package-registry)
-    - Create an empty npm project for easier installation (`npm init`) in the tools cache directory. You can delete `package.json`, `package.lock.json` and `node_modules` after all tools get installed
-    - Before downloading a specific package, create an empty folder for the version of Python/PyPY that is being installed. If downloading Python 3.6.8 for example, create `C:\hostedtoolcache\windows\Python\3.6.8`
-    - Once configured, download a specific package by calling `npm install`. Note (if downloading a PyPy package on Windows, you will need 7zip installed along with `7z.exe` added to your PATH)
-- Each NPM package has multiple versions that determine the version of Python or PyPy that should be installed. 
-    - `npm install @actions/toolcache-python-windows-x64@3.7.61579791175` for example installs Python 3.7.6 while `npm install @actions/toolcache-python-windows-x64@3.6.81579791177` installs Python 3.6.8
-    - You can browse and find all available versions of a package by searching the GitHub Actions NPM registry
-![image](https://user-images.githubusercontent.com/16109154/76194005-87aeb400-61e5-11ea-9b21-ef9111247f84.png)
+A few things to look out for when `setup-python` is first setting up the tools cache
+- If using Windows, your runner needs to be running as an administrator so that the appropriate directories and files can be setup. On Linux and Mac, you also need to be running with elevated permissions
+- On Windows, you need `7zip` installed and added to your `PATH` so that files can be extracted properly during setup
+- MSI installers are used when setting up Python on Windows. A word of caution as MSI installers update registry settings
+- The 3.8 MSI installer for Windows will not let you install another 3.8 version of Python. If `setup-python` fails for a 3.8 version of Python, make sure any previously installed versions are removed by going to "Apps and Features" in the Windows settings and uninstalling any
 
 # Using Python without `setup-python`
 
@@ -152,8 +137,6 @@ Python versions that we compile and setup can be found in the [actions/python-ve
   - certain modules might be missing
   - there is a version of Python that you would like that is currently not available
 
-If you suspect something might be wrong with the tools cache or how Python gets installed on GitHub hosted runners, please open an issue in [actions/virtual-environments](https://github.com/actions/virtual-environments)
-
 Any remaining issues can be filed in this repository
 
 # License