Update gorule-0000027.md

Found additional implementation points while looking at pombase/pombase-chado#1224 ; updating.
Tagging @mugitty @pgaudet

metadata/rules/gorule-0000027.md

@@ -8,7 +8,7 @@ status: implemented
 contact: "[email protected]"
 implementations:
   - language: python
-    source: https://github.com/biolink/ontobio/blob/master/ontobio/io/gafparser.py
+    source: https://github.com/biolink/ontobio/blob/master/ontobio/io/gafparser.py https://github.com/biolink/ontobio/blob/master/ontobio/io/assocparser.py
 ---
 -   DB (GAF and GPAD column 1); and all DB abbreviations in 'with' field (GAF column 8; GPAD column 7) and in the annotation extensions (GAF column 16; GPAD column 11) must be in [db-xrefs.yaml](https://github.com/geneontology/go-site/blob/master/metadata/db-xrefs.yaml) (see below)
 -   id_syntax information in the [db-xrefs.yaml](https://github.com/geneontology/go-site/blob/master/metadata/db-xrefs.yaml) file can be used to validate local identifiers.