Bug 1599027 - Remove http inspector doc. r=Honza.

The page was outdated and incorrect, so we remove it.
The architecture diagram of the console is updated to
show TabBoxPanel, and we add a quick summary for the
external components used in the Console.

Differential Revision: https://phabricator.services.mozilla.com/D54463

--HG--
extra : moz-landing-system : lando

devtools/docs/index.md

@@ -43,7 +43,6 @@
   * [Memory](tools/memory-panel.md)
   * [Debugger](tools/debugger-panel.md)
   * [Responsive Design Mode](tools/responsive-design-mode.md)
-  * [HTTP Inspector](tools/http-inspector.md)
   * [Console](tools/console-panel.md)
 * [Frontend](frontend/frontend.md)
   * [Panel SVGs](frontend/svgs.md)