DSEGOG-320 Update for Apache extension

[MRichards99]

This is a simple PR to support the changes made in https://github.com/ral-facilities/operationsgateway-ansible/pull/17. The og-api variable for the dev server has been edited to add /api onto the end of it. Also a couple of sentences in dev_server.md to explain this change.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.99%. Comparing base (0063ced) to head (82d869d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #124   +/-   ##
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  Coverage   94.99%   94.99%           
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  Files          50       50           
  Lines        2837     2837           
  Branches      297      297           
=======================================
  Hits         2695     2695           
  Misses        105      105           
  Partials       37       37           

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