ci(rstcheck): fix paths string

Paths are not checked recursively by default.

Signed-off-by: Randolph Sapp <[email protected]>

.github/workflows/rstcheck.yml

@@ -5,7 +5,7 @@ on:
   pull_request:
     branches: [master]
     paths:
-      - source
+      - 'source/**'
 
 defaults:
   run: