Let say within your markdown file in your gatsby project, you want to link to another page. Eg. you want to link to /about using [About](/about)
Thanks for this stackoverflow article, the answer is pretty simple.
- npm install gatsby-plugin-catch-links
- add gatsby-plugin-catch-links to gatsby-config.js
- write your link exactly as per example above (see the raw version of this page in the using-remark repo)