.spacemacs: reorder config layers, add comments

.spacemacs

@@ -32,8 +32,7 @@ This function should only modify configuration layer settings."
 
    ;; List of configuration layers to load.
    dotspacemacs-configuration-layers
-   '(javascript
-     systemd
+   '(
      ;; ----------------------------------------------------------------
      ;; Example of useful layers you may want to use right away.
      ;; Uncomment some layer names and press `SPC f e R' (Vim style) or
@@ -49,26 +48,32 @@ This function should only modify configuration layer settings."
      graphviz
      helm
      html
+     javascript
      latex
+     ;; https://github.com/emacs-lsp/lsp-mode
      (lsp :variables
           lsp-rust-server
           'rust-analyzer)
      markdown
+     ;; https://www.spacemacs.org/layers/+emacs/org/README.html
      (org :variables
           org-enable-roam-support t
           org-enable-roam-ui t)
      plantuml
      (python :variables python-backend 'lsp python-lsp-server 'mspyls)
+     ;; https://develop.spacemacs.org/layers/+lang/rust/README.html
      (rust :variables rust-backend 'lsp)
      shell
      ;; shell-scripts
      ;; spell-checking
      syntax-checking
+     systemd
      (tree-sitter :variables
                   spacemacs-tree-sitter-hl-black-list '(js-mode js2-mode)
                   tree-sitter-syntax-highlight-enable t
                   tree-sitter-fold-enable t
                   tree-sitter-fold-indicators-enable t)
+     (typescript-mode (typescript-backend . lsp))
      version-control
      yaml
      ;; (shell :variables