set documentation uri to googleapis.dev location (#840)

README.md

@@ -1,4 +1,4 @@
-# Google API Client [![RubyDoc](https://img.shields.io/badge/RubyDoc-Google%3A%3AApis-red.svg)](https://www.rubydoc.info/github/googleapis/google-api-ruby-client/Google/Apis) [![Gem Version](https://badge.fury.io/rb/google-api-client.svg)](https://badge.fury.io/rb/google-api-client)
+# Google API Client [![Documentation](https://img.shields.io/badge/docs-Google%3A%3AApis-red.svg)](https://googleapis.dev/ruby/google-api-client/latest/Google/Apis.html) [![Gem Version](https://badge.fury.io/rb/google-api-client.svg)](https://badge.fury.io/rb/google-api-client)
 
 These client libraries are officially supported by Google.  However, the libraries are considered complete and are in maintenance mode. This means that we will address critical bugs and security issues but will not add any new features.
 

google-api-client.gemspec

@@ -10,6 +10,9 @@ Gem::Specification.new do |spec|
   spec.summary       = 'Client for accessing Google APIs'
   spec.homepage      = 'https://github.com/google/google-api-ruby-client'
   spec.license       = 'Apache-2.0'
+  spec.metadata      = {
+    "documentation_uri" => "https://googleapis.dev/ruby/google-api-client/v#{Google::Apis::VERSION}"
+  }
 
   spec.files         = `git ls-files -z`
                        .split("\x0")