exclude site & docs from GH language stats

Author: aSemy

.gitattributes

@@ -58,3 +58,7 @@
 # Exclude files from exporting
 .gitattributes export-ignore
 .gitignore     export-ignore
+
+# https://github.com/github/linguist/blob/v7.24.1/docs/overrides.md
+docs/**         linguist-documentation
+site/**         linguist-documentation