Update shadertype.md - Githubissues

What does this PR do?

Thanks for the contribution! Please provide a concise description of the problem this request solves.

How does this PR change Premake's behavior?

Are there any breaking changes? Will any existing behavior change?

Anything else we should know?

Add any other context about your changes here.

Did you check all the boxes?

[v] Focus on a single fix or feature; remove any unrelated formatting or code changes
[ ] Add unit tests showing fix or feature works; all tests pass
[ ] Mention any related issues (put closes #XXXX in comment to auto-close issue when PR is merged)
[ ] Follow our coding conventions
[ ] Minimize the number of commits
[ ] Align documentation to your changes

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premake / premake-core