Add connectors attributes and main/master branch logic

Author: leemthompo

shared/attributes.asciidoc

@@ -270,6 +270,13 @@ Enterprise Search
 :ents: Enterprise Search
 :app-search-crawler: App Search web crawler
 
+:connectors-python: https://github.com/elastic/connectors/tree/{connectors-branch}
+
+:connectors-branch: {branch}
+ifeval::['{branch}' == 'master']
+:connectors-branch: main
+endif::[]
+
 //////////
 Ingest terms
 //////////