Added .md files from Collate + Updated DG

[ongweekeong]

1. Updated DG to a more consistent format for the Implementation Section
2. Updated DG to include the "read " command.
3. Updated DG to include the segments for Request Backup and Dispatch Backup commands in the Implementation section.
4. Added .md files for our current collate status. Will update again towards the deadline for v1.3 (especially for test code)

[codecov-io]

Codecov Report

Merging #153 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #153      +/-   ##
============================================
+ Coverage     39.37%   39.45%   +0.08%     
  Complexity      271      271              
============================================
  Files            63       63              
  Lines          1816     1812       -4     
  Branches        191      191              
============================================
  Hits            715      715              
+ Misses         1051     1047       -4     
  Partials         50       50

Impacted Files	Coverage Δ	Complexity Δ
src/seedu/addressbook/Main.java	0% <ø> (ø)	0 <0> (ø)	⬇️
src/seedu/addressbook/commands/InboxCommand.java	0% <ø> (ø)	0 <0> (ø)	⬇️
src/seedu/addressbook/password/Password.java	28.37% <100%> (ø)	40 <0> (ø)	⬇️

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[muhdharun]

Thanks for reformatting the DG, will ensure subsequent additions of implementations and other info follow the current format