Add some doc to the github actions / CI scripts (#8034)

* Add some doc to the githuib actions / CI scripts

Type: task

* alalytics-events is more name matching

.github/workflows/end-to-end-tests.yaml

@@ -1,4 +1,4 @@
-name: Develop
+name: End-to-end Tests
 on:
     # These tests won't work for non-develop branches at the moment as they
     # won't pull in the right versions of other repos, so they're only enabled
@@ -11,6 +11,7 @@ jobs:
     end-to-end:
         runs-on: ubuntu-latest
         env:
+          # This must be set for fetchdep.sh to get the right branch
           PR_NUMBER: ${{github.event.number}}
         container: vectorim/element-web-ci-e2etests-env:latest
         steps:

.github/workflows/layered-build.yaml

@@ -1,3 +1,5 @@
+# Produce a 'layered build' (a build of element-web with this version of
+# react-sdk) and output it as an artifact
 name: Layered Preview Build
 on:
     pull_request:
@@ -5,6 +7,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         env:
+          # This must be set for fetchdep.sh to get the right branch
           PR_NUMBER: ${{github.event.number}}
         steps:
             - uses: actions/checkout@v2

.github/workflows/netlify.yaml

@@ -1,3 +1,5 @@
+# Triggers after the layered build has finished, taking the artifact
+# and uploading it to netlify
 name: Upload Preview Build to Netlify
 on:
     workflow_run:

.github/workflows/test_coverage.yml

@@ -7,6 +7,7 @@ jobs:
   test-coverage:
     runs-on: ubuntu-latest
     env:
+      # This must be set for fetchdep.sh to get the right branch
       PR_NUMBER: ${{github.event.number}}
     steps:
       - name: Checkout code

.github/workflows/typecheck.yaml

@@ -6,6 +6,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         env:
+          # This must be set for fetchdep.sh to get the right branch
           PR_NUMBER: ${{github.event.number}}
         steps:
             - uses: actions/checkout@v2