Add sponsor link

Author: Dreamsorcerer

content/pages/projects/aiohttp.md

@@ -1,6 +1,7 @@
 Title: Aiohttp
 Links: Docs=https://docs.aiohttp.org/en/stable/
        Github=https://github.com/aio-libs/aiohttp/
+       Sponsor=https://opencollective.com/aio-libs/projects/aiohttp
 
 An asynchronous HTTP Client/Server for Python's [asyncio](https://docs.python.org/3/library/asyncio.html).