feature/lookup: rewrite dash docset integration

+ Uses alist variable to store config, rather than hooks
+ Added check for installed docsets in +lookup/documentation
+ Set docsets for various language modules (c-mode, c++-mode, css-mode,
  scss-mode, sass-mode, web-mode, go-mode, racket-mode, emacs-lisp-mode,
  js2-mode, rjsx-mode, typescript-mode, rust-mode, and php-mode)
+ Made *eww* popups for dash docsets larger
+ Renamed set-docset! => set-docsets! (set-docset! is aliased to
  set-docsets!)
+ New +lookup/install-docset alias

modules/lang/cc/config.el

@@ -41,6 +41,8 @@ compilation database is present in the project.")
 
   :config
   (set-electric! '(c-mode c++-mode objc-mode java-mode) :chars '(?\n ?\}))
+  (set-docsets! 'c-mode "C")
+  (set-docsets! 'c++-mode "C++" "Boost")
 
   (set-pretty-symbols! '(c-mode c++-mode)
     ;; Functional