Update the README

[satendrapalsingh]

Pitch As a developer new to the Chainblocks-Examples repository, I want to quickly understand and set it up, so that I may start contributing if interested.

Acceptance criteria Update this project repository's README file to satisfy the parent Epic's Acceptance Criteria, and additional criteria given below

• [x] Add link to building-chainblocks documentation
• [x] Run a grammar check on the finished text

Additional context Refer to guidelines at Github, freeCodeCamp, Make a Readme, & Awesome READMEs.

[satendrapalsingh]

Hey team! Please add your planning poker estimate with ZenHub @guusw @Kryptos-FR @sinkingsugar

[satendrapalsingh]

PR #9