Fixes#140.
Added a one-liner description about the date calculation functionality
Description of the changes:
* This change maintains consistency by writing it after the description of the programmer calculator so that it matches the order of the positions of these functionalities in the hamburger menu of the calculator.
* Just like the other descriptions, this is also a one-liner
* This description covers both the functionality under "date calculation" i.e. the difference between the dates and adding/subtracting a date from another.
Co-Authored-By: sonali9696 <sonali9696@gmail.com>
Removing the team contact email address from the README and disabled it from
accepting incoming mail from external users. We want to encourage open communication
with the community, and so would prefer to defer all communication to open channels
whenever possible.
