Fix typo in GitHub Dependency Graph submission text (#5772)

Please open all PRs as drafts and ensure that your fork of Mill has 
`settings/actions` / `Allow all actions and reusable workflows` enabled
to run CI on
your own fork of the Mill repo. Only once CI passes mark the PR as
`Ready for review`
and CI will run on the main Mill repo before we merge it.

Author: nafg

website/docs/modules/ROOT/pages/extending/thirdparty-plugins.adoc

@@ -418,7 +418,7 @@ object `jvm-project` extends JavaModule, GitVersionedPublishModule {
 
 == GitHub Dependency Graph Submission
 
-A plugin to submit your mill dependency graph to GiHub through their
+A plugin to submit your mill dependency graph to GitHub through their
 https://github.blog/2022-06-17-creating-comprehensive-dependency-graph-build-time-detection/[Dependency
 Submission API].