GitHub: Link to headers in READMEs

Anytime you add a header to a markdown file, GitHub attaches an href with its downcased name. ‘JavaScript’ receives a link to #javascript, for instance.

Leverage this by adding a table of contents to your README with links to the headers further down the document:

### Table of Contents

-   [Cucumber](#cucumber)

This will link to a header containing ‘Cucumber’.

h/t Josh Branchaud

Via jwworth/til.