.github: Create lint-rst.yaml
.github: Create lint-rst.yaml

This is a Github workflow for automatic checking and catching malformed
RST files on PRs.

It can also be manually triggered from the Github Actions UI for testing
with the following options:

- rstcheck report type
- RST files to find
- Paths to find

Fixes: #13366

Signed-off-by: Geyslan G. Bem <f4b1cbbbea5f92f5c62d2b429aae4742785e210f@accuknox.com>

cilium/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium