Update godot documentation contribution link

Hey there, first time contributing and I'm in the middle of reading the contribution best practice, so sorry for any mistakes in this pull request. 

When clicking the **Contributing section** link under the **Contributors guidelines** title, this linked to the Godot *page not found* link.

I changed the link from `https://docs.godotengine.org/en/latest/contributing/ways_to_contribute.html` to `https://docs.godotengine.org/en/latest/contributing/how_to_contribute.html`.

Now, when a user clicks the link, it will redirect them to the start of the contribution documentation.

CONTRIBUTING.md

@@ -3,7 +3,7 @@
 This document summarizes the most important points for people interested in
 contributing to Godot, especially via bug reports or pull requests.
 
-The Godot documentation has a dedicated [Contributing section](https://docs.godotengine.org/en/latest/contributing/ways_to_contribute.html)
+The Godot documentation has a dedicated [Contributing section](https://docs.godotengine.org/en/latest/contributing/how_to_contribute.html)
 which details these points and more, and is a recommended read.
 
 ## Table of contents
@@ -63,7 +63,7 @@ In addition to the following tips, also take a look at the
 [Engine development guide](https://docs.godotengine.org/en/latest/contributing/development/index.html)
 for an introduction to developing on Godot.
 
-The [Contributing docs](https://docs.godotengine.org/en/latest/contributing/ways_to_contribute.html)
+The [Contributing docs](https://docs.godotengine.org/en/latest/contributing/how_to_contribute.html)
 also have important information on the [PR workflow](https://docs.godotengine.org/en/latest/contributing/workflow/pr_workflow.html)
 (with a helpful guide for Git usage), and our [Code style guidelines](https://docs.godotengine.org/en/latest/contributing/development/code_style_guidelines.html)
 which all contributions need to follow.