Add design docs

[cijothomas]

Part of #2570
This adds an initial draft of Logs architecture/design. Will add Metrics one next, and then Traces (Traces would be mostly same as Logs)

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (3)

docs/design/logs.md:111

• The phrase should be 'components like the exporter use interior mutability'.

components like exporter use interior mutability

docs/design/logs.md:117

• The phrase should be 'ownership is not passed to the processor.'.

ownership is not passed to the processor

docs/design/logs.md:123

• The phrase should be 'Since the processor only gets a reference to the log, it cannot store it beyond OnEmit().'

Since the processor only gets a reference to the log, it cannot store it beyond the `OnEmit()`.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.1%. Comparing base (1aca212) to head (55698d3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2657   +/-   ##
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  Coverage   79.1%   79.1%           
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  Files        120     120           
  Lines      22556   22556           
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  Hits       17857   17857           
  Misses      4699    4699           

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[lalitb]

nit - However, since this is public API, there is nothing preventing it from being used by end-users.

[lalitb]

Thanks, @cijothomas! This is a great addition for anyone looking to understand the design and revisit the reasoning behind certain decisions. I haven't completed the full review yet. so added minor (cosmetic) comments on the parts I've reviewed so far.

[scottgerring]

This is great (and I learnt some stuff reading it) !

[lalitb]

LGTM. Thanks for adding this :)

[cijothomas]

Merging as the doc is still marked experimental/draft. Will be polishing the doc more to cover more design decisions.
Please continue to share feedback or even send a PR to modify the design doc itself.