switch CI and signing policy from master to main branch

.github/workflows/release.yml

@@ -7,7 +7,7 @@ permissions: read-all
 
 on:
   push:
-    branches: [master]
+    branches: [main]
     tags: ['v*']
   pull_request:
 
@@ -26,14 +26,14 @@ jobs:
           cargo deny check advisories bans
       - run: cargo doc --no-deps --document-private-items --workspace
       - name: Upload doc artifact
-        if: github.ref == 'refs/heads/master'
+        if: github.ref == 'refs/heads/main'
         uses: actions/upload-pages-artifact@v5
         with:
           path: target/doc
 
   pages:
     needs: check
-    if: github.ref == 'refs/heads/master'
+    if: github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
     permissions:
       contents: read

docs/CODE_SIGNING_POLICY.md

@@ -56,6 +56,6 @@ designed to respect user privacy by never sending data anywhere.
 > SignPath yet.  This policy exists for transparency and privacy
 > documentation while the project prepares for certification.
 
-Only binaries produced by the official CI runner from the `master`
+Only binaries produced by the official CI runner from the `main`
 branch will be submitted to SignPath for signing.  Manual or off-CI
 builds are never shipped as signed releases.