Update CONTRIBUTING.md

Author: tidwall

.github/CONTRIBUTING.md

@@ -9,18 +9,13 @@ Before getting starting with contributing, please know that we currently use [Ti
 - **Ensure the bug was not already reported** by searching on GitHub under [Issues](https://github.com/tidwall/tile38/issues).
 - If you're unable to find an open issue addressing the problem, [open a new one](https://github.com/tidwall/tile38/issues/new). Be sure to include a **title and clear description**, as much relevant information as possible, and a **code sample** or an **executable test case** demonstrating the expected behavior that is not occurring.
 
-### Did you write a patch that fixes a bug?
-
-- Open a new GitHub pull request with the patch.
-- Ensure the PR description clearly describes the problem and solution. Include the relevant issue number if applicable.
-
 ### Did you fix whitespace, format code, or make a purely cosmetic patch?
 
 Changes that are cosmetic in nature and do not add anything substantial to the stability, functionality, or testability of Tile38 will generally not be accepted.
 
 ### Do you intend to add a new feature or change an existing one?
 
-- Suggest your change in [a new issue](https://github.com/tidwall/tile38/issues/new) or in the [Tile38 Slack](https://tile38.com/slack), and start writing code.
-- Do not open an issue on GitHub until you have collected positive feedback about the change. GitHub issues are primarily intended for bug reports and fixes.
+- New features will probably not be approved without prior discussion. If you need a specialized feature, make sure to express your willingness to fund the work and maintenance.
+- Please do not open a pull request without filing an issue and/or discussing it with a maintainer beforehand.
 
-Thanks!
+Thanks!