Proper documentation for syntax

[MarcellPerger1]

We need proper documentation for the syntax/feature of this language so that:

• If someone finds this and is interested (unlikely tbh), they have idea of what the syntax looks like without diving into the code
• I don't forget how the syntax works if I come back to this after a year of not doing working on this

[MarcellPerger1]

Especially since the syntax doesn't perfectly match any single language.
In its current state, the syntax is equal parts Python and JavaScript, with a hint of Java and Lua.