add Firebase to redirects

Author: sarah11918

public/_redirects

@@ -41,7 +41,7 @@
 /:lang/reference/experimental-flags/responsive-images/				     /:lang/guides/images/
 /:lang/guides/deploy/sst/														/:lang/guides/deploy/aws-via-sst/
 /:lang/guides/deploy/flightcontrol/									/:lang/guides/deploy/aws-via-flightcontrol/
-
+/:lang/guides/deploy/google-firebase/						/:lang/guides/deploy/firebase/
 
 
 # Very old docs site redirects