docs: Link bats HOWTO directly to abs github URL

Fixes #68

Author: kakawait

website/content/docs/contributing/how-to-contribute.md

@@ -37,7 +37,7 @@ several ways you can help us :
 
 ### Write bats tests
   If you have spotted a bug, a great way to help us improve toml bombadil is to write a
-  [bats](https://bats-core.readthedocs.io/en/latest/) test to reproduce it, see [HOWTO](bats-tests/HOWTO.md) for more info.
+  [bats](https://bats-core.readthedocs.io/en/latest/) test to reproduce it, see [HOWTO](https://github.com/oknozor/toml-bombadil/blob/main/bats-tests/HOWTO.md) for more info.
 
 ### Suggesting new features