Update PR checks readme instructions

pr-checks/readme.md

@@ -1,23 +1,14 @@
 # PR Checks
 
-This folder contains the code supporting the workflows run when a PR is created.
+This folder contains the workflow generator that must be run in order to create the
+workflows used by the CodeQL Action CI. Workflows must be recreated after any change
+to one of the files in this directory.
 
-## Update
-
-If you need to make a change to any of the PR checks, you need to perform the following
-steps:
-
-1. Make the change - the code for the PR checks is under the `pr-checks/checks/` folder.
-2. Run the `sync.py` file to produce (and sync) the final workflow files under `.github/`
-
-The second part requires some associated steps (create a virtual environment, download
-the dependencies for the Python script, etc), so we have automated this with the `justfile`
-included in this folder.
-
-### 1-step update
+## Updating workflows
 
 1. Install https://github.com/casey/just by whichever way you prefer.
-2. Run `$ just update-pr-checks` in your terminal.
+2. Run `just update-pr-checks` in your terminal.
+
+### If you don't want to intall `just`
 
-If you don't wish to install `just`, you can also manually perform the steps
-outlined in the `justfile` under the `update-pr-checks` action.
+Manually run each step in the `justfile`.