Fix spelling mistakes

[moritzdietz]

First of I want to say congratulations on launching this beautiful Matrix client! 👏🏻

When browsing the main site, I noticed some small mistakes

• Sometimes the spelling was wrong and I fixed it without changing your wording much
• Matrix the protocol needs to be capitalized
• Cinny seems to be capizalized as well, so I made sure it was capitalized in all places where it makes sense
• The apostrophe needs to go on DMs

And I've taken the liberty to change this phrase: Cinny is built over matrix to Cinny is built on top of Matrix Cross reference: https://techcrunch.com/2021/07/27/element-a-messaging-app-built-on-the-decentralized-matrix-protocol-raises-30m

[kfiven]

Thanks @moritzdietz