r&d: filter by c++ & build files

Hopefully to avoid builds during document updates

Author: malachib

.github/workflows/idf.yml

@@ -3,6 +3,12 @@ name: ESP-IDF
 on:
   push:
     branches: [ "dev/**", "alpha" ]
+    paths:
+      - '**/.c??'
+      - '**/.h??'
+      - '**/.yml'
+      - '**/CMakeLists.txt'
+      - '**/*.cmake'
 
 jobs:
   build: