Push changelog to Readme.com automatically

[p-maguire]

Similar to a few of our other projects (Java, Node.js, Python), we should process and push our changelog to Readme.com when we run a release job.

Reference:

• https://github.com/bitpay/nodejs-bitpay-client/blob/8.0.x/.github/workflows/release.yml

Requirements

• Create a new workflow called release
• Running the release job manually should ask for branch, version (instead of major, minor, patch), and overview
• Update readme.txt automatically
• Update file headers automatically
• Automatically create the tag and release
• Automatically push to Readme.com changelog API