fix(slangd): use .slang instead of .shaderslang for slang

[mTvare6]

The extension used by slang is .slang.
Examples and docs for reference.

[lithammer]

This isn't a file extension though. It's a filetype¹.

Footnotes

1. https://vimhelp.org/filetype.txt.html ↩

[mTvare6]

My bad, but neovim itself doesn't have a shaderslang filetype yet either way.

[lithammer]

Seems like the filetype was added to nvim-treesitter. So you would need that and enable "slang" for his to make sense.

The filetype shaderslang is a invention of myself, but I plan to also use it for a tree-sitter parser nvim-treesitter/nvim-treesitter#5659 and a TBD PR to vim for filetype detection. shaderslang is used because Vim/Neovim already has support for a filetype called slang which I assume is for https://en.wikipedia.org/wiki/S-Lang with extension *.sl while shaderslang uses *.slang.

• feat: add support for slangd #2907
• parsers: add tree-sitter-slang nvim-treesitter/nvim-treesitter#5659

[mTvare6]

Vim now supports shaderslang