Update README.md

README.md

@@ -12,6 +12,26 @@ One must have installed these utilities to start development:
 - Go
 - Node
 
+### MacOS
+
+If you're using MacOS, ```corepack``` is also needed. Corepack ships with Node, but zsh does not find this linkage in the shell. Therefore, since we are using brew, corepack can be installed with:
+
+```brew install corepack```
+
+Brew may error and say that you must remove the symlink for ```yarn``` if you used brew to install yarn. Do not fret, run this command:
+
+```brew unlink yarn```
+
+Then, rerun ```brew install corepack```.
+
+Now, run ```corepack enable```. This will enable corepack globally. Optionally, one can run ```corepack install --global yarn@stable``` to install the latest yarn version globally using corepack.
+
+To set the yarn version in the frontend directory, first ```cd frontend``` then ```corepack use yarn@v```, where ```v``` is the version you want to set. In this project, we are using stable, so the command would be ```corepack use yarn@stable```.
+
+#### Aside
+
+Corepack is used in the GitHub workflow file to make ensure yarn can install.
+
 ## Software
 
 Below is a list of software one may use to code this project:
@@ -116,4 +136,4 @@ We must implement endpoint testing.
 
 Here are software development terms that may be unfamiliar and are found during the development process.
 
-- [Triage](https://dictionary.cambridge.org/dictionary/english/triage)
+- [Triage](https://dictionary.cambridge.org/dictionary/english/triage)