data: add react mumbai meetup (#6396)

Author: ehteshamdev0

src/content/community/meetups.md

@@ -101,6 +101,7 @@ Do you have a local React.js meetup? Add it here! (Please keep the list alphabet
 * [Bangalore (React Native)](https://www.meetup.com/React-Native-Bangalore-Meetup)
 * [Chennai](https://www.meetup.com/React-Chennai/)
 * [Delhi NCR](https://www.meetup.com/React-Delhi-NCR/)
+* [Mumbai](https://reactmumbai.dev)
 * [Pune](https://www.meetup.com/ReactJS-and-Friends/)
 
 ## Indonesia {/*indonesia*/}