doc: how to set DOTNET_ROOT

Author: scivision

Readme.md

@@ -39,10 +39,15 @@ The
 "backend" column tells which functions have selectable backend implementations.
 By default, when the "backend" is not specified to a function having selectable backend, the algorithm searches for the first available backend and uses that.
 
-
-* [.NET](https://www.mathworks.com/help/matlab/call-net-from-matlab.html)
+[.NET](https://www.mathworks.com/help/matlab/call-net-from-matlab.html)
+support in MATLAB includes:
   * Windows: all supported Matlab releases
-  * Linux / macOS: R2024b and newer
+  * Linux or macOS: R2024b and newer
+
+For macOS, `brew install dotnet` and then in Matlab `edit(fullfile(userpath, 'startup.m'))` and add the line `setenv('DOTNET_ROOT', '/opt/homebrew/opt/dotnet/libexec')` where the path is determined from `brew --prefix dotnet`.
+
+Other language backends include:
+
 * [Java](./Readme_java.md): all supported Matlab releases
 * [Perl](https://www.mathworks.com/help/matlab/ref/perl.html):  Matlab R2018a and newer. This uses a system() call to Perl.
 * [Python](https://www.mathworks.com/help/matlab/call-python-libraries.html): Matlab R2022b and newer. `stdlib.has_python` checks that the Python version set by `pyenv()` is compatible with the Matlab release.