docs: add detailed design for datarouter and mw/log components

[RSingh1511]

Notes for Reviewer

Pre-Review Checklist for the PR Author

• PR title is short, expressive and meaningful
• Commits are properly organized
• Relevant issues are linked in the References section
• Tests are conducted
• Unit tests are added

Checklist for the PR Reviewer

• Commits are properly organized and messages are according to the guideline
• Unit tests have been written for new behavior
• Public API is documented
• PR title describes the changes

Post-review Checklist for the PR Author

• All open points are addressed and tracked via issues

References

Closes #

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.3.0) and connecting to it...
INFO: Invocation ID: 0d6496ee-ac85-4052-a4e3-90ba7664cdf4
Computing main repo mapping: 
WARNING: For repository 'score_crates', the root module requires module version score_crates@0.0.9, but got score_crates@0.0.10 in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off
Computing main repo mapping: 
Loading: 
Loading: 4 packages loaded
Loading: 4 packages loaded
    currently loading: 
WARNING: Target pattern parsing failed.
ERROR: Skipping '//:license-check': no such target '//:license-check': target 'license-check' not declared in package '' defined by /home/runner/work/logging/logging/BUILD
ERROR: no such target '//:license-check': target 'license-check' not declared in package '' defined by /home/runner/work/logging/logging/BUILD
INFO: Elapsed time: 5.239s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

[rmaddikery]

The detailed design needs to direct the users to existing detailed design documentation and not generate more text that is obvious from the sources.