Add /oss page with hyperlinked upstream contribution blurbs.

Readable sectioned tour of merged PRs; project names link to GitHub.
Navbar gains an OSS entry.

Author: VedantMadane

_config.yml

@@ -25,6 +25,7 @@ navbar-links:
   Play:
     - Pakshī: "https://vedantmadane.github.io/pakshi/"
     - Dānav: "https://vedantmadane.github.io/krida/danav/"
+  OSS: "oss"
   Resume: "https://vedantmadane.github.io/resume/"
   About: "https://vedantmadane.github.io/aboutme"
 #  Resources: