Developer Guide: Update UI section

[yanghengtang]

• Updated UI section (Closes #278)
• Add planned enhancement for NRIC (Closes #261)
• Add planned enhancement for Phone (Closes #263)
• Add planned enhancement for Remarks (Closes #265)
• Updated Logic section (Closes #279)

[codecov[bot]]

Codecov Report

Merging #292 (281474e) into master (9f449bd) will not change coverage. Report is 3 commits behind head on master. The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #292   +/-   ##
=========================================
  Coverage     80.68%   80.68%           
  Complexity      938      938           
=========================================
  Files           137      137           
  Lines          2837     2837           
  Branches        277      277           
=========================================
  Hits           2289     2289           
  Misses          513      513           
  Partials         35       35           

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