README: use a softer tone

#1426 contains a mixture of opinions/feedback:

1. That `fascists can go f*k themselves` is a political statement - [I firmly believe that it is not the case](https://github.com/hexops/mach/issues/1426#issuecomment-3065896795) and have no qualms about stating that anywhere.

2. That although it is not a political statement, its tone is aggressive in nature which may be deterring for people looking at the project.

Originally, the community moderation statement here was an explicit non-exclusion of LGBTQ+ people - similar to this one - but as part of adding this statement to the README I had adjusted it to be perceived as 'less political' to certain readers.

After feedback and reflection, I am restoring this version which - while still arguably 'just as political' by certain readers - offers a softer and less aggressive tone.

README.md

@@ -19,5 +19,4 @@ Zig game engine & graphics toolkit for building high-performance, truly cross-pl
 
 Join the [Mach community on Discord](https://discord.gg/XNG3NZgCqp) to discuss this project, ask questions, get help, etc.
 
-**We're here to make games and have fun, so please help keep the community focused on that.** No politics/heated topics are allowed. Unfortunately, the political landscape today makes it such that we must also state fascists can go f*k themselves. :) Anyone else is very welcome here.
+**We're here to make games and have fun, so please help keep the community focused on that.** Do not escalate or engage in heated topics. LGBTQ+ people's existence is not political. Everyone is very welcome here. 💛
-