limit documentation workflow runs for relevant changes. (#7125)

Author: sayakpaul

.github/workflows/build_documentation.yml

@@ -7,6 +7,10 @@ on:
       - doc-builder*
       - v*-release
       - v*-patch
+    paths:
+      - "src/diffusers/**.py"
+      - "examples/"
+      - "docs/"
 
 jobs:
   build:

.github/workflows/build_pr_documentation.yml

@@ -2,6 +2,10 @@ name: Build PR Documentation
 
 on:
   pull_request:
+    paths:
+      - "src/diffusers/**.py"
+      - "examples/"
+      - "docs/"
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}