docs: flatten H4 subheadings in Vim/Neovim and Emacs sections

The Vim/Neovim and Emacs sections each had two H4 subheadings, pushing
the sidebar TOC three levels deep. Replace the H4s with bold leading
phrases so the page reads the same but the sidebar collapses to two
levels.

Author: bartlomieju

runtime/getting_started/setup_your_environment.md

@@ -87,10 +87,9 @@ vim.lsp.config('ts_ls', {
 This assumes a `deno.json` or `deno.jsonc` lives at the root of your Deno
 project.
 
-#### Kickstart.nvim and Mason LSP
-
-If you use [kickstart.nvim](https://github.com/nvim-lua/kickstart.nvim), add the
-equivalent configuration to the `servers` table in your `init.lua`:
+**Kickstart.nvim and Mason LSP.** If you use
+[kickstart.nvim](https://github.com/nvim-lua/kickstart.nvim), add the equivalent
+configuration to the `servers` table in your `init.lua`:
 
 ```lua
 local servers = {
@@ -108,9 +107,8 @@ local servers = {
     }
 ```
 
-#### Other Vim/Neovim plugins
-
-If you prefer a different plugin ecosystem, Deno also works with the following:
+**Other Vim/Neovim plugins.** If you prefer a different plugin ecosystem, Deno
+also works with the following:
 
 - **[ALE](https://github.com/dense-analysis/ale):** supports the Deno language
   server out of the box. See
@@ -185,21 +183,15 @@ config.deno.enable = true
 
 ### Emacs
 
-#### lsp-mode
-
-Emacs supports Deno via the Deno language server using
+**lsp-mode.** Emacs supports Deno via the Deno language server using
 [lsp-mode](https://emacs-lsp.github.io/lsp-mode/). Once
 [lsp-mode is installed](https://emacs-lsp.github.io/lsp-mode/page/installation/)
 it should support Deno, which can be
 [configured](https://emacs-lsp.github.io/lsp-mode/page/lsp-deno/) to support
 various settings.
 
-#### eglot
-
-You can also use built-in Deno language server by using
-[`eglot`](https://github.com/joaotavora/eglot).
-
-An example configuration for Deno via eglot:
+**eglot.** You can also use the built-in Deno language server via
+[`eglot`](https://github.com/joaotavora/eglot). An example configuration:
 
 ```elisp
 (add-to-list 'eglot-server-programs '((js-mode typescript-mode) . (eglot-deno "deno" "lsp")))