CI: buildpackage workflow: documentation links

.github/workflows/ubuntu.yml

@@ -1,4 +1,10 @@
 name: buildpackage
+# Goal: produce .deb files on Ubuntu >= 22.04 (jammy) or Debian >= 12 (bookworm/bullseye-backports)
+# https://wiki.debian.org/Packaging
+# https://www.debian.org/doc/debian-policy/
+# https://www.debian.org/doc/packaging-manuals/python-policy/
+
+# https://docs.github.com/articles/events-that-trigger-workflows
 on:
   push:
     tags:
@@ -8,7 +14,7 @@ on:
     paths:
       - .github/workflows/ubuntu.yml
   workflow_dispatch:
-  # allow manual trigger
+  # https://docs.github.com/articles/configuring-a-workflow#manually-running-a-workflow
 
 permissions:
   contents: read # to fetch code (actions/checkout)
@@ -17,15 +23,17 @@ env:
   # note that some tools care only for the name, not the value
   FORCE_COLOR: 1
 
-  # reduce metadata, unlike elsewhere, build artifacts should differ by content only
+  # reduce metadata. unlike elsewhere, build artifacts should differ by content only
   SOURCE_DATE_EPOCH: 0
 
 jobs:
   lint:
     name: buildpackage-${{ matrix.python-version }}
+    # https://docs.github.com/articles/virtual-environments-for-github-actions
     runs-on: ubuntu-latest
     strategy:
       fail-fast: true
+      # https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstrategymatrix
       matrix:
         python-version: [ "os-py" ]
     steps: