Change default branch from master to default

Author: zakkak

.github/workflows/repo-sync.yml

@@ -3,14 +3,15 @@ name: Repo Sync
 on:
   push:
     branches:
-    - master
+    - default
     paths:
     - .github/workflows/**
   schedule:
   - cron: '0 4 * * *'
 
 jobs:
-  mandrel-master:
+  graal-master:
+    name: Keep graal/master in sync with upstream master
     runs-on: ubuntu-latest
     steps:
     - name: Checkout graal/master branch
@@ -26,3 +27,19 @@ jobs:
         git fetch upstream master
         git merge --ff-only upstream/master
         git push --quiet origin graal/master
+  mandrel-master:
+    name: Keep master in sync with default
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout graal/master branch
+      uses: actions/checkout@v2
+      with:
+        ref: master
+        fetch-depth: 0
+    - name: Sync branch
+      run: |
+        git config --local user.email "fzakkak@redhat.com"
+        git config --local user.name "Foivos Zakkak through GH action"
+        git fetch origin default
+        git merge --ff-only origin/default
+        git push --quiet origin master

CONTRIBUTING.md

@@ -16,12 +16,12 @@ To contribute please fork this repository and open a pull request (PR).
 
 ## Repository Structure
 
-Mandrel, being a downstream distribution of GraalVM CE, is not developed on the master branch.
+Mandrel, being a downstream distribution of GraalVM CE, is not developed on the `default` branch.
 Instead version specific branches, based on the corresponding GraalVM CE release, are used for development and maintenance. 
 For instance, Mandrel 20.1.x.x releases are developed in the `mandrel/20.1` branch.
 Similarly, Mandrel 20.2.x.x releases are developed in the `mandrel/20.2` branch and so on.
 
-The `master` branch is used only as a landing page and for hosting some housekeeping github actions workflows and templates.
+The `default` branch is used only as a landing page and for hosting some housekeeping github actions workflows and templates.
 
 In addition to the `mandrel/XX.Y` branches Mandrel also includes `graal/X` branches like `graal/master`.
 These branches are mirrors of the corresponding upstream branch and are being synchronized and tested nightly, in an effort to detect breaking changes upstream as soon as possible.