Stabilize Node.js to 16.20.0 for all uses and developer docs

.github/workflows/test.yml

@@ -9,7 +9,13 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
+      - name: Use Node.js from .nvmrc
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: '.nvmrc'
+          cache: 'npm'
+          cache-dependency-path: 'yarn.lock'
       - name: Install Dependencies
         run: yarn
       - name: Test

.npmrc

@@ -0,0 +1 @@
+registry = 'https://registry.yarnpkg.com'

.nvmrc

@@ -0,0 +1 @@
+16.20.0

README.md

@@ -53,3 +53,22 @@ If no `version-command` input is provided, this action will attempt to do someth
  - If it finds single `*.gemspec` file, it will consider the version defined there to be the repository version.
 
 The logic for this detection and the corresponding version commands used can be found in [`determine-version.ts`](src/determine-version.ts).
+
+## Developing
+
+To work on this repo do the following after cloning:
+
+```bash
+# Use exact version of Node.js as detailed in .nvmrc file
+nvm install
+
+# If you don't have Yarn v1 installed globally then use this to install
+# dependencies in the repo as it's used for package management.
+npm install --no-save yarn@1
+
+# Install dependencies with yarn
+npx yarn install
+
+# Run end to end build and validation
+npm run all
+```