add format documentation links

Problem: I wanted to know what color schema is available
Solution: Add links to directly reach the predefined schemes and templates

INSTALL.md

@@ -77,12 +77,17 @@ The format is the following:
   /* … Or… */
   "colorA": "#555",
   "colorB": "#4c1",
-  /* See template/ for a list of available templates.
+  /* See templates/ for a list of available templates.
      Each offers a different visual design. */
   "template": "flat"
 }
 ```
 
+See also
+
+- [colorscheme.json](colorscheme.json) for the `colorscheme` option
+- [templates/](templates) for the `template` option
+
 # Defaults
 
 If you want to add a colorscheme, head to `lib/colorscheme.json`. Each scheme