Fix repeated TOC entries

Author: cspotcode

doc/index.rst

@@ -73,8 +73,8 @@ The Python Arcade Library
    :maxdepth: 1
    :caption: Programming Guide
 
-   programming_guide/install/index
    programming_guide/get_started
+   programming_guide/install/index
    programming_guide/sprites/index
    programming_guide/how_to_get_help
    programming_guide/edge_artifacts/index
@@ -88,7 +88,6 @@ The Python Arcade Library
    programming_guide/gui/index
    programming_guide/performance_tips
    programming_guide/sections
-   programming_guide/index
 
 .. image:: images/API.svg
    :alt: API icon
@@ -114,10 +113,6 @@ The Python Arcade Library
    programming_guide/release_notes
    License <https://github.com/pythonarcade/arcade/blob/development/license.rst>
    contributing_guide/index
-   contributing_guide/directory_structure
-   contributing_guide/how_to_contribute
-   contributing_guide/how_to_submit_changes
-   contributing_guide/release_checklist
 
 .. image:: images/social.svg
    :alt: Social icon