Add parameter to control version script (#23)

* Add version script

* Run build

Co-authored-by: mitchellhamilton <mitchell@hamil.town>

README.md

@@ -24,7 +24,7 @@ jobs:
       - name: Checkout Repo
         uses: actions/checkout@master
         with:
-          # This makes Actions fetch all Git history so that Changesets can generate changelogs with the correct commits 
+          # This makes Actions fetch all Git history so that Changesets can generate changelogs with the correct commits
           fetch-depth: 0
 
       - name: Setup Node.js 12.x
@@ -61,10 +61,9 @@ jobs:
       - name: Checkout Repo
         uses: actions/checkout@master
         with:
-          # This makes Actions fetch all Git history so that Changesets can generate changelogs with the correct commits 
+          # This makes Actions fetch all Git history so that Changesets can generate changelogs with the correct commits
           fetch-depth: 0
 
-
       - name: Setup Node.js 12.x
         uses: actions/setup-node@master
         with:
@@ -82,3 +81,44 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
 ```
+
+### With version script
+
+If you need to add additional logic to the version command, you can do so by using a version script.
+
+If the version script is present, this action will run that script instead of `changeset version`, so please make sure that your script calls `changeset version` at some point. All the changes made by the script will be included in the PR.
+
+```yml
+name: Release
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  release:
+    name: Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repo
+        uses: actions/checkout@master
+        with:
+          fetch-depth: 0
+
+      - name: Setup Node.js 12.x
+        uses: actions/setup-node@master
+        with:
+          node-version: 12.x
+
+      - name: Install Dependencies
+        run: yarn
+
+      - name: Create Release Pull Request
+        uses: changesets/action@master
+        with:
+          # this expects you to have a npm script called version that runs some logic and then calls `changeset version`.
+          version: yarn version
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+```