add repo creation and customization instructions

Author: gregsdennis

README.md

@@ -1,3 +1,12 @@
 # JSON Schema Repository Template
 
 You've stumbled upon our template repository.  The sole purpose of this repository is to make creating new repositories easier.
+
+# Using the template
+
+1. Follow the [Github instructions](https://docs.github.com/en/repositories/creating-and-managing-repositories/creating-a-repository-from-a-template) to create your repo.
+2. Update _README.md_ to be project-specific rather than this file.
+3. Update _CONTRIBUTING.md_ with any additional or project-specific guidelines.
+4. Update your new repo settings, if desired.  This repo sets:
+   - Require PRs for changes to `main`
+   - Require an approval for all PRs