Fix Pedantic Grammar/Syntax Issues In README.md

[rynstwrt]

FIXES:

• Change "Allows the connection of older clients to..." to "Allows older clients to connect to..."
• Remove extra period.
• Change "early-access" to "early access"
• Change sentence addition after a comma to be a separate sentence.
• Change "open source" to "open-source"

Sorry 😭 I saw the double period and went to fix it and noticed more stuff.

[FormallyMyles]

I'd personally say that apart from the extra period and a slight increase in conciseness to the first line, the other changes aren't really needed.

[rynstwrt]

I feel you. I would say the comma addition part to a new sentence is more necessary than the hyphenation changes but less important than the double period and the concision of the client connection line, Just thought I'd include really small stuff while I was at it :P

[FlorianMichael]

Apart from the extra review, I agree with myles.

[FlorianMichael]

Thanks :)