docs: add missing keywords

[dy-tea]

When I was working on a pr to c2v I noticed there were quite a few keywords missing from the Keywords section of the docs.

This may be intentional because most of these are type names but I can confirm that all of these are reserved by the compiler and therefore cannot be used as variable names.

I am unsure about dump because it is part of the ast but is technically a function.

Let me know if any changes should be made.

_{Huly®: V_0.6-21725}

[spytheman]

I think that the type names should be listed separately, and not as part of the keyword list.

Keep in mind, that you can for example do -no-builtin, and have V compile code without string, array or map defined (or implement them yourself).

You can not do that with actual keywords, without modifying the compiler.

[dy-tea]

Yeah the only question is if dump should be considered a keyword or not, otherwise there is no difference. It may make sense to have a Reserved Tokens sections as it makes certain projects easier (e.g. syntax highlighters).