Update README.md

[blacko3]

I changed twitter to X
It had to be done

[CLAassistant]

All committers have signed the CLA.

[pallavjha25]

I understand the intent behind this change, and all marking of twitter should be renamed to X, but the links are broken if used with X instead of twitter.

e.g.
https://blog.x.com/en_us/topics/company/2023/a-new-era-of-transparency-for-X - is broken. 👎
https://blog.x.com/en_us/topics/company/2023/a-new-era-of-transparency-for-twitter - is working. 👍
https://blog.x.com/engineering/en_us/topics/open-source/2023/X-recommendation-algorithm - is broken. 👎