Fix documentation errors and prescription input/duplicate bug

[huyuxin0429]

Added check at parser level to only allow alphanumeric and certain characters:
Fixes #217
Fix addPrescription command to check the name of prescription when adding.
Fixes #210

Fix documentation bugs
Fixes #200
Fixes #198
Fixes #197
Fixes #196

[codecov-commenter]

Codecov Report

Merging #232 (d002a4c) into master (599f6ad) will decrease coverage by 0.08%.
The diff coverage is 22.22%.

@@             Coverage Diff              @@
##             master     #232      +/-   ##
============================================
- Coverage     51.96%   51.87%   -0.09%     
  Complexity      552      552              
============================================
  Files           119      119              
  Lines          2413     2421       +8     
  Branches        271      273       +2     
============================================
+ Hits           1254     1256       +2     
- Misses         1068     1073       +5     
- Partials         91       92       +1     

Impacted Files	Coverage Δ
...c/main/java/seedu/docit/commons/core/Messages.java	0.00% <ø> (ø)
...ava/seedu/docit/model/appointment/Appointment.java	32.25% <0.00%> (-2.23%)	⬇️
...va/seedu/docit/logic/parser/AddressBookParser.java	93.10% <50.00%> (-6.90%)	⬇️

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[gycgabriel]

LGTM

[gycgabriel]

Unsure if this has been fixed as can't find relevant parser edits in files changed

Added check at parser level to only allow alphanumeric and certain characters:
Fixes #217

[gycgabriel]

LGTM