Adding crowdin.yml to .gitignore

[GuardsmanPanda]

To remove the risk of committing API keys while testing the Crowdin integration.

[alerque]

To remove the risk of committing API keys

Reduce not remove. You can still add files to git tracking even if they are ignored, either by using --force or having a user config that ignores ignore files, or using Git tooling besides the official client that doesn't properly check the list, or any number of other ways. But yes this does reduce the risk ;-)