Merge pull request #817 from JoFrhwld/master

Edit to macOS C++ install docs

src/cmdstan-guide/installation.qmd

@@ -351,36 +351,39 @@ or cluster administrator to install these tools for you.
 
 #### MacOS
 
-To install a C++ development
-environment on a Mac, use Apple's Xcode development environment
-https://developer.apple.com/xcode/.
-
-From the [Xcode home page](https://developer.apple.com/xcode/)
-`View in Mac App Store`.
-
-- From the App Store, click `Install`, enter an Apple ID, and wait
-for Xcode to finish installing.
--  Open the Xcode application, click top-level menu `Preferences`,
-click top-row button `Downloads`, click button for
-`Components`, click on the `Install` button to the right of
-the `Command Line Tools` entry, then wait for it to finish
-installing.
-- Click the top-level menu item `Xcode`, then click item `Quit
-Xcode` to quit.
-
-To test, open the Terminal application and enter:
+To check if you already already have an appropriate toolchain
+installed, open the Terminal application and enter:
 ```
 clang++ --version
 make --version
 ```
 
-If you have installed XCode, but don't have `make`, you can install the
-XCode command-line tools via command:
+If either of these commands prints the message 
+`command not found`, you will need to install Xcode's
+command line tools.
+
+Open the Terminal application and enter:
+
 ```
 xcode-select --install
 ```
 
+Select "Install" in the window that opens.
+
+After the installation completes, you can double check that
+installation was successful by reopening the Terminal and 
+running:
+```
+clang++ --version
+make --version
+```
+
+You can read more about Xcode on its site: 
+[https://developer.apple.com/xcode/](https://developer.apple.com/xcode/)
 
+We don't recommend trying to use the GNU C++ compiler, available via Homebrew,
+based on the number of reports of installation difficulties from Mac users on GitHub
+as well as the Stan forums.
 
 #### Windows {#windows}