chore: update repo-metadata.json client_documentation link (#636)

* chore: updating doc link

* chore: fix missing comma

Author: eaball35

.repo-metadata.json

@@ -2,7 +2,7 @@
   "name": "spanner-jdbc",
   "name_pretty": "Google Cloud Spanner JDBC",
   "product_documentation": "https://cloud.google.com/spanner/docs/use-oss-jdbc",
-  "client_documentation": "https://googleapis.dev/java/google-cloud-spanner-jdbc/latest/index.html",
+  "client_documentation": "https://cloud.google.com/java/docs/reference/google-cloud-spanner-jdbc/latest/history",
   "release_level": "ga",
   "language": "java",
   "min_java_version": 8,