Document pre-commit checks; update instructions for submitting sample files

_includes/links.md

@@ -11,6 +11,7 @@
 [wiki]: https://github.com/openslide/openslide/wiki
 [testdata]: https://openslide.cs.cmu.edu/download/openslide-testdata/
 [snapshots]: /builds/
+[submit-sample]: /submit/
 
 [doc-dev]: /#development
 [doc-debugopts]: /docs/debugopts/

docs/devguide/index.md

@@ -33,19 +33,27 @@ addressing feedback from code review, edit your existing commits with `git
 rebase -i` and update the branch with `git push -f`, rather than appending
 fixup commits to the branch.
 
+OpenSlide uses Git hooks and the [pre-commit][pre-commit] framework to
+check coding style when you commit.  To configure the hooks, install
+pre-commit from your package manager or with `pip install pre-commit`, then
+run `pre-commit install` in your OpenSlide checkout.  The pre-commit checks
+are also rerun as part of OpenSlide's CI.
+
 Please discuss your changes on the [openslide-users][users-subscribe]
 mailing list or in a GitHub issue, *before* you are ready to submit them, so
 that we can help you integrate your code into the existing codebase.
 
 When contributing support for a new format, we *strongly* prefer that you
-also contribute example slide files for our [openslide-testdata][testdata]
-repository.  The example files must be data that you are entitled to
-contribute, and the OpenSlide project must receive permission to
-redistribute them with or without modification.  Email the mailing list for
-instructions on how to accomplish this.
+also [contribute example slide files][submit-sample] for our
+[openslide-testdata][testdata] repository.  The example files must be data
+that you are entitled to contribute, and the OpenSlide project must receive
+permission to redistribute them under the [Creative Commons Zero][cc0]
+license.  See the [submission form][submit-sample] for more details.
 
 [rjones]: https://people.redhat.com/~rjones/how-to-supply-code-to-open-source-projects/
 [rjones-splitting-commits]: https://people.redhat.com/~rjones/how-to-supply-code-to-open-source-projects/#split_patches
+[pre-commit]: https://pre-commit.com/
+[cc0]: https://creativecommons.org/publicdomain/zero/1.0/legalcode
 
 
 ## Original development guide

docs/newformat/index.md

@@ -231,7 +231,7 @@ common cleanup label.  `g_autoptr()` is suitable for structs with their own
 free functions, and `g_autofree` is for arbitrary memory that can be freed
 with `g_free()`.  Variables declared with `g_auto*` must always be
 initialized on the spot (perhaps to `NULL`) to avoid freeing a garbage
-pointer; CI has a check for this.
+pointer; pre-commit checks include a test for this.
 
 When allocating an object that will be returned from the function, or will
 be linked into data structures that outlive the function, prefer using