docs: Add Tailwind configuration section for JavaScript/TypeScript (#45057)

Addresses some tasks in #43969. Namely adding TailwindCSS documentation
for the following languages: HTML, JavaScript and Typescript.

**Some Notes**
- Maybe the additional information in the HTML section is unnecessary,
unsure open to suggestions.
- I tried utilizing capturing groups with alternatives like
`\\.(add|remove|toggle|contains)` but this didn't seem to work, so I was
forced to use multiple lines.

Release Notes:

- N/A

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

docs/src/languages/javascript.md

@@ -175,6 +175,34 @@ You can configure ESLint's `workingDirectory` setting:
 }
 ```
 
+## Using the Tailwind CSS Language Server with JavaScript
+
+To get all the features (autocomplete, linting, etc.) from the [Tailwind CSS language server](https://github.com/tailwindlabs/tailwindcss-intellisense/tree/HEAD/packages/tailwindcss-language-server#readme) in vanilla JavaScript files (`.js`), you can customize the `classRegex` field under it in your `settings.json`:
+
+```json [settings]
+{
+  "lsp": {
+    "tailwindcss-language-server": {
+      "settings": {
+        "experimental": {
+          "classRegex": [
+            "\\.className\\s*[+]?=\\s*['\"]([^'\"]*)['\"]",
+            "\\.setAttributeNS\\(.*,\\s*['\"]class['\"],\\s*['\"]([^'\"]*)['\"]",
+            "\\.setAttribute\\(['\"]class['\"],\\s*['\"]([^'\"]*)['\"]",
+            "\\.classList\\.add\\(['\"]([^'\"]*)['\"]",
+            "\\.classList\\.remove\\(['\"]([^'\"]*)['\"]",
+            "\\.classList\\.toggle\\(['\"]([^'\"]*)['\"]",
+            "\\.classList\\.contains\\(['\"]([^'\"]*)['\"]",
+            "\\.classList\\.replace\\(\\s*['\"]([^'\"]*)['\"]",
+            "\\.classList\\.replace\\([^,)]+,\\s*['\"]([^'\"]*)['\"]"
+          ]
+        }
+      }
+    }
+  }
+}
+```
+
 ## Debugging
 
 Zed supports debugging JavaScript code out of the box with `vscode-js-debug`.
@@ -186,7 +214,7 @@ The following can be debugged without writing additional configuration:
 Run {#action debugger::Start} ({#kb debugger::Start}) to see a contextual list of these predefined debug tasks.
 
 > **Note:** Bun test is automatically detected when `@types/bun` is present in `package.json`.
->
+
 > **Note:** Node test is automatically detected when `@types/node` is present in `package.json` (requires Node.js 20+).
 
 As for all languages, configurations from `.vscode/launch.json` are also available for debugging in Zed.