build: allow to trigger docs workflow manually

GitOrigin-RevId: 46b624ecbebfcb89214a3af9e4cc89a80df25a88
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e9fe052..d63e8c4 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -6,6 +6,7 @@
       - main
     paths:
       - 'docs/**'
+  workflow_dispatch:
 
 jobs:
   build: