docs: ref docs URL for Page Sharer

data/page_sharer.toml

@@ -1,3 +1,6 @@
+# Page Sharer
+# Documentation: https://sourcethemes.com/academic/docs/customization/#page-sharer
+
 [[buttons]]
   id = "twitter"
   url = "https://twitter.com/intent/tweet?url={url}&text={title}"