Update opportunities page with additional open source programs

[sagesharp]

The opportunities page has a section titled "More opportunities" that is meant to have programs where people can learn about open source software. The emphasis is on paid opportunities.

@tapaswenipathak has an awesome list of open source opportunities. However, it may be outdated, since it was last updated in 2019.

Your goal, should you choose to accept it, is to merge @tapaswenipathak's list with the "More opportunities" section in the Outreachy website opportunities page. The HTML file for the opportunities page is here. The focus for Outreachy's opportunities page should be paid opportunities to work on open source.

Tasks:

• [ ] Remove the entry for Recurse Center (they're not completely open source focused, although recursers could study open source if they want)
• [ ] Split the Outreachy "More opportunities" section into "More job boards" and "Paid opportunities in open source"
• [ ] Categorize all entries under the old "More opportunities" section as a paid opportunity or a job board
• [ ] Move all entries from @tapaswenipathak's "SOC-program" section to the new "Paid opportunities in open source" section but only if the opportunity pays a stipend, and the program is still running
• [ ] Done!

[sagesharp]

Additional summer of code programs:

• Chinese summer of open source - verify whether applicants need to speak mandarian?
• European Summer of Weather Code