Fixed API docs generation

[sergeyklay]

Hello!

• Type: bug fix
• Link to issue: API Documentation: Incorrect Namespace on type hinted return. #1229

In raising this pull request, I confirm the following:

• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I updated the CHANGELOG

Small description of change:

• Fixed incorrect namespace on type hinted return when generating API docs
• Cleaned up Documentation namespace
• Cleaned up API templates

Thanks

[codecov]

Codecov Report

Merging #1998 into development will not change coverage.
The diff coverage is 0%.

@@              Coverage Diff               @@
##             development    #1998   +/-   ##
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  Coverage          34.33%   34.33%           
  Complexity          8162     8162           
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  Files                561      561           
  Lines              45204    45204           
==============================================
  Hits               15521    15521           
  Misses             29683    29683