reorganize docs structure

Author: takase1121

docs/developer-guide/renderer-internals.md renamed to docs/developer-guide/advanced-topics/renderer-internals.md

@@ -2,6 +2,8 @@
 description: An introduction about Lite XL's concepts and how they tie in to plugin development.
 ---
 
+# Developer Guide
+
 Lite XL has little functionalities without plugins — anything that can be implemented as plugins can
 and _will_ be implemented as one.
 
@@ -43,4 +45,4 @@ Follow [this guide][9] to learn how it works.
 [6]: https://github.com/rxi/lite
 [7]: https://rxi.github.io/lite_an_implementation_overview.html
 [8]: https://github.com/lite-xl/lite-xl-plugins/blob/master/plugins/lite-debugger.lua?raw=1
-[9]: ./debugging.md
+[9]: ./writing-plugins/debugging.md

docs/developer-guide/commands.md renamed to docs/developer-guide/commands-and-shortcuts/commands.md

@@ -157,9 +157,9 @@ return toolbar
 ```
 
 
-[screenshot-toolbarview]: ../assets/screenshots/views/toolbarview.png
-[drag-n-drop]:            ../assets/screenshots/views/drag-n-drop.png
-[red-button]:             ../assets/screenshots/views/red-button.png
-[customize-codes]:        ../assets/screenshots/views/customize-codes.png
+[screenshot-toolbarview]: ../../assets/screenshots/views/toolbarview.png
+[drag-n-drop]:            ../../assets/screenshots/views/drag-n-drop.png
+[red-button]:             ../../assets/screenshots/views/red-button.png
+[customize-codes]:        ../../assets/screenshots/views/customize-codes.png
 [learning-lua]:           https://www.lua.org/pil/contents.html
 [fontello]:               https://fontello.com/

docs/developer-guide/managing-keyboard-shortcuts.md renamed to docs/developer-guide/commands-and-shortcuts/managing-keyboard-shortcuts.md

@@ -182,6 +182,6 @@ It's not recommended changing these values unless you know what you're doing.
 
 
 [lite-xl-colors]: https://github.com/lite-xl/lite-xl-colors/blob/master/colors/dracula.lua
-[basic-layout]:   ../assets/developer-guide/creating-themes/basic-layout.png
-[scrollbar]:      ../assets/developer-guide/creating-themes/scrollbar.png
-[nagbar]:         ../assets/developer-guide/creating-themes/nagbar.png
+[basic-layout]:   ../../assets/developer-guide/creating-themes/basic-layout.png
+[scrollbar]:      ../../assets/developer-guide/creating-themes/scrollbar.png
+[nagbar]:         ../../assets/developer-guide/creating-themes/nagbar.png