SDKS-4947 Updating README with maintenance information

[rodrigoareis]

JIRA Ticket

SDKS-4947 Update README files

Description

A new section has been added to the top of the README file to communicate that this repository is officially in maintenance mode.

Definition of Done Checklist:

• Coded to standards.
• Ensure backward compatibility.
• API reference docs is created or updated, if applicable.
• Unit tests are written or updated.
• Integration tests are written, if applicable.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.75%. Comparing base (2baa722) to head (d065f8f).

Additional details and impacted files

@@              Coverage Diff              @@
##             develop     #515      +/-   ##
=============================================
- Coverage      65.77%   65.75%   -0.03%     
  Complexity      1764     1764              
=============================================
  Files            264      264              
  Lines           8658     8658              
  Branches         969      969              
=============================================
- Hits            5695     5693       -2     
- Misses          2532     2534       +2     
  Partials         431      431              

Flag	Coverage Δ
unit-tests	65.75% <ø> (-0.03%)	⬇️

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