CI: run once per change, and skip documentation-only changes (#28)

Author: bdbarnett

.github/workflows/tests.yml

@@ -1,9 +1,18 @@
 name: Extension tests
 
+# Documentation-only changes can't change this result, so they don't run it.
 on:
-  pull_request:
   push:
     branches: [main]
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+      - 'LICENSE'
+  pull_request:
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+      - 'LICENSE'
 
 permissions:
   contents: read