Add documentation for scope manager omission (ot-shim: document the omission of scope manager #2700)

[Asheklm6]

Which problem is this PR solving?

This PR addresses the missing documentation related to the omission of the "Scope Manager" in the OpenTelemetry shim for OpenTracing. The scope manager was never implemented, and this PR adds a note about that omission to inform developers.

Fixes #2700.

Short description of the changes

• Added a new documentation file (SCOPE_MANAGER_OMISSION.md) that describes the omission of the scope manager in the OpenTelemetry shim for OpenTracing.
• The documentation informs developers that there is no support for a scope manager and provides context to avoid confusion.

Type of change

• This change requires a documentation update

How Has This Been Tested?

This is a documentation-only change, so no tests were required.

• No code changes to test

Checklist:

• Followed the style guidelines of this project
• [] Unit tests have been added (Not applicable since it's a documentation update)
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Asheklm6 / name: Aisha Kamsalem (2291119, 6fc1c27, a29d35c)

[pichlermarc]

@Asheklm6 thanks for opening this PR. 🙂

Would you mind adding this documentation to packages/opentelemetry-shim-opentracing/README.md instead?
I think there it could be more visible to users.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.27%. Comparing base (f8ab559) to head (a29d35c).
Report is 28 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5039      +/-   ##
==========================================
- Coverage   93.39%   93.27%   -0.13%     
==========================================
  Files          46      317     +271     
  Lines         712     8194    +7482     
  Branches      120     1640    +1520     
==========================================
+ Hits          665     7643    +6978     
- Misses         47      551     +504     

see 266 files with indirect coverage changes

[Asheklm6]

@pichlermarc Thank you for the feedback, I have looked into it and I have rectified it, pls can you look into it if it meets the requirements.