All samples must have READMEs about ruby-docs-samples

[frankyn]

Notes for AppEngine Readme's

• Analytics

1. Setup analytics could have a link to: https://support.google.com/analytics/answer/1032385?hl=en
2. README redirects a person to the parent appengine directory

• Static Page

1. Should link to https://cloud.google.com/appengine/docs/flexible/ruby/serving-static-files

• Sendgrid

1. State the version of the API we are using and link to the API docs for Sendgrid as well.
2. Maybe even directly linking to the gem: https://github.com/sendgrid/sendgrid-ruby

• CloudSQL

1. Describe what the sample is doing, similar to Cloud Datastore README.

• Metadata

1. Describe what the sample is doing, (Displaying the IP address of the instance)

• Pubsub

1. Describe what the sample is doing. How it works and what's expected.

[broady]

Closing, please re-open (and re-assign) if still relevant.

If re-opening, probably best to change it to P2.