refine repos based on the latest contribution rules (#632)

Based on the criteria outlined in this [thesis](https://scholar.uwindsor.ca/etd/5879) and the [paper](https://www.researchgate.net/publication/343154514_A_Large-Scale_Dataset_of_Popular_Open_Source_Projects) on popular open-source projects, we have refined the contribution threshold to 500 stars, offering a clearer definition of "production-level" repositories.

Author: zhimin-z

CONTRIBUTING.md

@@ -5,7 +5,7 @@ Thank you for your interest in contributing to the awesome production machine le
 When proposing a new tool or section, please keep the following in mind:
 
 * This list is meant to highlight notable tools, not to be an exhaustive directory.
-* Tools should have a minimum of 300 stars on GitHub.
+* Tools should have a minimum of 500 stars on GitHub.
 * Tools should not be listed in more than one section.
 * Tools should not be archived and must have been actively maintained within the last 6 months.
 * Ensure that all contributions are listed in alphabetical order within their respective sections.