Bug 1536103 - Removed some unused devtools in tree placeholder documentation.r=firefox-source-docs-reviewers,sylvestre

Differential Revision: https://phabricator.services.mozilla.com/D73499

devtools/docs/backend/backend.md

@@ -1,2 +0,0 @@
-
-These files provide information about general backend architecture.

devtools/docs/frontend/frontend.md

@@ -1,2 +0,0 @@
-
-These files provide information about general frontend architecture.

devtools/docs/index.rst

@@ -64,7 +64,6 @@ Tool Architectures
 .. toctree::
    :maxdepth: 1
 
-   Tool Architectures <tools/tools.md>
    Inspector Panel Architecture <tools/inspector-panel.md>
    Inspector Highlighters <tools/highlighters.md>
    Memory <tools/memory-panel.md>
@@ -79,7 +78,6 @@ Frontend
 .. toctree::
    :maxdepth: 1
 
-  Frontend <frontend/frontend.md>
   Panel SVGs <frontend/svgs.md>
   React <frontend/react.md>
   React Guidelines <frontend/react-guidelines.md>
@@ -94,7 +92,6 @@ Backend
 .. toctree::
    :maxdepth: 1
 
-   Backend <backend/backend.md>
    Remote Debugging Protocol <backend/protocol.md>
    Client API <backend/client-api.md>
    Debugger API <backend/debugger-api.md>

devtools/docs/tools/tools.md

@@ -1,2 +0,0 @@
-
-These files provide a high-level overview of each tool and how they work.