Fix bug regarding messages for Patients and update UG

[kohkaijie]

Made changes to the format method in Messages.java to add patient fields if the person to be added/deleted is a patient.

Updated UG for adding patient and doctors to remove duplicate information already mentioned in the parameters table as well as potential errors when adding unspecified prefixes. This addresses the issue in #193.

Do help look through the phrasing for how i addressed the above issue as it may not be the most complete.

Attached below is my email to prof Damith verifying that the above bug fix does not violate the feature freeze.

The second commit entails the following minor UG changes:

• Ensuring all sentences have full stops.
• All duplicate information already included in the parameter table have been removed.
• Minor grammar mistakes corrected.
• Update Undo and Redo sections to inform users that exiting the app will prevent them from undoing or redoing their previous actions.

[codecov[bot]]

Codecov Report

Merging #217 (5e3885d) into master (c6594dd) will increase coverage by 0.08%. The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master     #217      +/-   ##
============================================
+ Coverage     72.20%   72.28%   +0.08%     
- Complexity      724      725       +1     
============================================
  Files           112      112              
  Lines          2547     2555       +8     
  Branches        274      275       +1     
============================================
+ Hits           1839     1847       +8     
  Misses          601      601              
  Partials        107      107              

Files	Coverage Δ
src/main/java/seedu/address/logic/Messages.java	70.58% <100.00%> (+9.04%)	:arrow_up:

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