Add kegg to providers

dbxref/providers.yaml

@@ -96,8 +96,19 @@
   retriever:
       type: 'internal'
       location: 'dbxref.retrieve.gene_ontology'
+- name: KEGG
+  prefixes: ["KO"]
+  resources:
+      html: ["https://www.genome.jp/dbget-bin/www_bget?%i"]
+      text: ["http://rest.kegg.jp/get/%i"]
+  check_existence: "http://rest.kegg.jsdjkaap/get/%i"
+  # not implemented yet
+  # retriever:
+  #    type: 'internal'
+  #    location: 'dbxref.retrieve.kegg'
 - name: HTTP
   prefixes: ["http", "https"]
   resources:
       html: ["%d:%i"]
   check_existence: "%d:%i"
+