[#3] Reviewed HTTP Basic chapter
[#3] Reviewed HTTP Basic chapter

- Normalisation: all references to "HTTP Basic" use the same capitalization now.
- Bracketed string for images is the alt tag, not the filename; substituted relevant image
  descriptions.
- Status codes, header names, and filenames should be enclosed in code tags.

ezimuel/apigility-documentation,PowerKiKi/apigility-documentation,santiph/apigility-documentation,poisa/apigility-documentation