docs: add a contributing guide for typos-lsp (#70)

This includes a basic guide for setting up the development environment
in terms of the rust side (server) as well as the editor side (client).

Currently instructions are provided for Neovim.

I verified the setup works for me (as in, I see errors in neovim 🙂) and
also consulted what seemed to be your dotfiles for reference
([link](https://github.com/tekumara/setup/blob/master/dotfiles/.config/nvim/init.lua#L21-L39))

---------

Co-authored-by: Oliver Mannion <[email protected]>

CONTRIBUTING.md

@@ -0,0 +1,45 @@
+# Contributing to `typos-lsp`
+
+This document contains information on how to contribute to the `typos-lsp` crate, which is the implementation of the Language Server Protocol (LSP) server.
+
+The source code of `typos-lsp` can be found in the [crates/typos-lsp/](./crates/typos-lsp/) directory.
+
+Make sure you have installed the rust toolchain with [rustup](https://rust-lang.github.io/rustup/index.html).
+
+## Setting up your development environment
+
+### How to run tests
+
+```sh
+cargo test
+```
+
+### How to run the LSP server locally for development
+
+First, compile the LSP server:
+
+```sh
+cargo build
+```
+
+Next, configure your editor to launch the LSP server.
+
+#### Running locally in Neovim
+
+For example, in Neovim, you can use the [sample neovim LSP config](docs/neovim-lsp-config.md) in the following way:
+
+```lua
+-- Set the path of the LSP server to the compiled binary on your disk
+require('lspconfig').typos_lsp.setup({
+  -- ... other settings from the example
+  cmd = { "/Users/me/git/typos-lsp/target/debug/typos-lsp" },
+})
+```
+
+To test your configuration, you can use the following methods:
+
+- open e.g. [crates/typos-lsp/tools/test.txt](crates/typos-lsp/tools/test.txt). You should see errors when opening the file.
+- you can also run `:LspInfo` in Neovim to see the status of the LSP server.
+- you can run `cargo clean` in the root directory of the project. After this, you can make sure Neovim displays errors when opening a file. Once finished, run `cargo build` to fix this
+
+<!-- markdownlint-disable-file line-length -->

README.md

@@ -53,3 +53,7 @@ Config files will be read from the workspace folder or its parents. If there is
 ## Why aren't my misspellings being corrected?
 
 To minimise false-positives `typos` only suggests corrections for known misspellings, rather than unknown words like a traditional spell-checker. For more info see [Why was ... not corrected?](https://github.com/crate-ci/typos?tab=readme-ov-file#why-was--not-corrected).
+
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md) to get started.