Add relevant "appendix" reference link for @KBLayout, @MUILang and @OSLang

[genius257]

Add link to the "appendix" for the macro's: @KBLayout, @MUILang and @OSLang

Currently the helper text does not include the link for the appendix.

the appendix link: https://www.autoitscript.com/autoit3/docs/appendix/OSLangCodes.htm