feat(emacs.d): Configure Sly for Common Lisp

Sets up Lisp modes in Sly REPL and points at the local hyperspec
checkout.

In fact the Hyperspec bit should probably be managed by Nix, but one
step at a time.

tools/emacs/config/init.el

@@ -182,6 +182,14 @@
 (use-package nginx-mode)
 (use-package rust-mode)
 
+(use-package sly
+  :hook ((sly-mrepl-mode . (lambda ()
+                             (paredit-mode)
+                             (rainbow-delimiters-mode-enable)
+                             (company-mode))))
+  :config
+  (setq common-lisp-hyperspec-root "file:///home/tazjin/docs/lisp/"))
+
 (use-package telega
   :bind (:map global-map ("s-t" . telega))
   :config (telega-mode-line-mode 1))