Fix duplicate path separator in URL mappings

Some URL mapping constants for specific port projects were defining
duplicate path separators (1). The value of the `ROUTE_ROOT` constant
is set to `/` and the port constants contained the partial path
`${ROUTE_ROOT}/` resulting in duplicate path separators `//`.
This has be fixed by removing the extra `/` character leaving only the
correct `ROUTE_ROOT` constant that resolves into a single path
separator.

References:
  (1) https://github.com/arcticicestudio/nord-docs/blob/53b712c02342b76516b918adb0b3c181d624c6fc/src/config/routes/mappings.js#L364-L412

Fixes GH-169

src/config/routes/mappings.js

@@ -361,55 +361,55 @@ const ROUTE_PORTS = ROUTE_ROOT + PORTS;
  * @constant {string}
  * @since 0.19.0
  */
-const ROUTE_PORTS_ATOM_UI = `${ROUTE_ROOT}/${PORTS}/atom-ui`;
+const ROUTE_PORTS_ATOM_UI = `${ROUTE_ROOT}${PORTS}/atom-ui`;
 
 /**
  * The route mapping for the "Nord dircolors" port project page.
  *
  * @constant {string}
  * @since 0.18.0
  */
-const ROUTE_PORTS_DIRCOLORS = `${ROUTE_ROOT}/${PORTS}/dircolors`;
+const ROUTE_PORTS_DIRCOLORS = `${ROUTE_ROOT}${PORTS}/dircolors`;
 
 /**
  * The route mapping for the "Nord Emacs" port project page.
  *
  * @constant {string}
  * @since 0.17.0
  */
-const ROUTE_PORTS_EMACS = `${ROUTE_ROOT}/${PORTS}/emacs`;
+const ROUTE_PORTS_EMACS = `${ROUTE_ROOT}${PORTS}/emacs`;
 
 /**
  * The route mapping for the "Nord JetBrains" port project page.
  *
  * @constant {string}
  * @since 0.12.0
  */
-const ROUTE_PORTS_JETBRAINS = `${ROUTE_ROOT}/${PORTS}/jetbrains`;
+const ROUTE_PORTS_JETBRAINS = `${ROUTE_ROOT}${PORTS}/jetbrains`;
 
 /**
  * The route mapping for the "Nord tmux" port project page.
  *
  * @constant {string}
  * @since 0.16.0
  */
-const ROUTE_PORTS_TMUX = `${ROUTE_ROOT}/${PORTS}/tmux`;
+const ROUTE_PORTS_TMUX = `${ROUTE_ROOT}${PORTS}/tmux`;
 
 /**
  * The route mapping for the "Nord Vim" port project page.
  *
  * @constant {string}
  * @since 0.13.0
  */
-const ROUTE_PORTS_VIM = `${ROUTE_ROOT}/${PORTS}/vim`;
+const ROUTE_PORTS_VIM = `${ROUTE_ROOT}${PORTS}/vim`;
 
 /**
  * The route mapping for the "Nord Visual Studio Code" port project page.
  *
  * @constant {string}
  * @since 0.15.0
  */
-const ROUTE_PORTS_VISUAL_STUDIO_CODE = `${ROUTE_ROOT}/${PORTS}/visual-studio-code`;
+const ROUTE_PORTS_VISUAL_STUDIO_CODE = `${ROUTE_ROOT}${PORTS}/visual-studio-code`;
 
 /**
  * The per-route unique `id` attribute values of sections components.