docs: refactor

docs/manual/languages/lsp.md

@@ -0,0 +1,16 @@
+# LSP Custom Packages/Command {#sec-languages-custom-lsp-packages}
+
+In any of the `opt.languages.<language>.lsp.package` options you can provide your own LSP package, or provide
+the command to launch the language server, as a list of strings.
+
+You can use this to skip automatic installation of a language server, and instead
+use the one found in your `$PATH` during runtime, for example:
+
+```nix
+vim.languages.java = {
+  lsp = {
+    enable = true;
+    package = ["jdt-language-server" "-data" "~/.cache/jdtls/workspace"];
+  };
+}
+```