Add note about symlink required for contributing documentation to build.
<render type="markdown">
<render-source key="index" file="../../../README.md"/>
<render-source key="coding" file="../../../CODING.md"/>
- <!-- This needs to be uncommented when generating the contributing doc. We are currently unable to get Docker in Docker running correctly in CI. -->
+ <!-- This needs to be uncommented when generating the contributing doc. We are currently unable to get Docker in Docker running correctly in CI. Note that a symlink must be created from /home/[test-user]/pgbackrest to /backrest. -->
<!-- <render-source key="contributing" file="../../../CONTRIBUTING.md"/> -->
<render-source key="test" file="../../../test/README.md"/>
<render-source key="documentation" file="../../README.md"/>
