Update DG with Add and Delete Role features

[jinnhl]

• Developer Guide now includes the implementation and design consideration of add and delete role features.
• Implementation ordering changed to be more intuitive to users.
• State reasons for why some features are omitted.
• Add note to User Guide demo to reminder users not to follow demo and examples blindly.

[codecov-commenter]

Codecov Report

Merging #290 (30e355c) into master (db55055) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #290   +/-   ##
=========================================
  Coverage     68.87%   68.87%           
  Complexity      705      705           
=========================================
  Files           107      107           
  Lines          2201     2201           
  Branches        258      258           
=========================================
  Hits           1516     1516           
  Misses          601      601           
  Partials         84       84           

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