Add gerrit.wikimedia.org to content_scripts.matches

I can live loading the extension with local hacks, but I do ask end
users to test new features/plugins and having to build the plugin would
be an extra step.

The manifest `content_scripts.matches` can probably be replaced by a
dynamic declaration which would be fed by some local configuration (see
`chrome.scripting.registerContentScripts()`).  Meanwhile simply add
`https://gerrit.wikimedia.org/r/*` to the list.

Google-Bug-Id: b/287605771
Release-Notes: Add https://gerrit.wikimedia.org/r/* to allowed hosts
Change-Id: Ieb71740a9f9582f75f90ad739e12cc1b92707a91
diff --git a/src/manifest.json b/src/manifest.json
index 57f3e04..77d9eb6 100644
--- a/src/manifest.json
+++ b/src/manifest.json
@@ -19,7 +19,8 @@
       "matches": [
         "https://*.git.corp.google.com/*",
         "https://*.staging-git.corp.google.com/*",
-        "https://*.googlesource.com/*"
+        "https://*.googlesource.com/*",
+        "https://gerrit.wikimedia.org/r/*"
       ],
       "js": [
         "content_script.js"