fix(purescript-language-server): root dir for Nix files #1954

As seen in the source code:
https://github.com/nwolverson/purescript-language-server/blob/db5584d79e698b02e3df12a1299d5f93262bd5ee/src/LanguageServer/IdePurescript/Main.purs#L391

Nix-related files were added to the Language server to establish the
root. This commit looks to mimic that behavior. The PureScript community
has a lot of Nix-positive users and tooling.

Additionally the docs were updated::
* Reflect the new `root_dir` + `root_pattern` list
* Include a list of ways to install the language server to your project
* Remove the specific, problematic npm install command because
** Globally installing these tools is a bad practice as teams should
   maintain consistent versions in their projects and users are less
   likely to remember to upgrade global packages; new documentation
   suggests to add it to your project, but it doesn’t _not_ say to
   install it globally if desired
** npm is _not_ the only JavaScript package manager
** JavaScript package managers are not the only way to get the language
   server
** Unrelated but technically incorrect: the block was labeled as a shell
   script despite it being a shell session (code block syntax `sh`
   should be `console`)

1 files changed, 7 insertions, 6 deletions

diff --git a/lua/lspconfig/server_configurations/purescriptls.lua b/lua/lspconfig/server_configurations/purescriptls.lua
index 495133d2..7010d57d 100644
--- a/lua/lspconfig/server_configurations/purescriptls.lua
+++ b/lua/lspconfig/server_configurations/purescriptls.lua
@@ -11,18 +11,19 @@ return {
   default_config = {
     cmd = cmd,
     filetypes = { 'purescript' },
-    root_dir = util.root_pattern('bower.json', 'psc-package.json', 'spago.dhall'),
+    root_dir = util.root_pattern('bower.json', 'psc-package.json', 'spago.dhall', 'flake.nix', 'shell.nix'),
   },
   docs = {
     description = [[
 https://github.com/nwolverson/purescript-language-server
-`purescript-language-server` can be installed via `npm`
-```sh
-npm install -g purescript-language-server
-```
+
+The `purescript-language-server` can be added to your project and `$PATH` via
+
+* JavaScript package manager such as npm, pnpm, Yarn, et al.
+* Nix under the `nodePackages` and `nodePackages_latest` package sets
 ]],
     default_config = {
-      root_dir = [[root_pattern("spago.dhall, 'psc-package.json', bower.json")]],
+      root_dir = [[root_pattern('spago.dhall', 'psc-package.json', 'bower.json', 'flake.nix', 'shell.nix'),]],
     },
   },
 }