Update-Markdown now supports v2

[jsuereth]

This takes an approach where we have guaranteed strings to access portions of the resolved schema:

registry. vs. refinements. access those portions, then, you can dive deeper via the signal type, e.g. registry.spans.{id}, refinements.events.{id}

For no good reason, I added registry.attributes.{id} if you want to pull an attribute snippet.

[codecov]

Codecov Report

❌ Patch coverage is 80.62500% with 62 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.6%. Comparing base (648b3a6) to head (773254f).
⚠️ Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/weaver_semconv_gen/src/v2.rs	73.0%	48 Missing ⚠️
crates/weaver_semconv_gen/src/parser.rs	91.1%	8 Missing ⚠️
crates/weaver_semconv_gen/src/lib.rs	86.2%	4 Missing ⚠️
crates/weaver_semconv_gen/src/v1.rs	88.2%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1064     +/-   ##
=======================================
+ Coverage   79.4%   79.6%   +0.1%     
=======================================
  Files         98      99      +1     
  Lines       7329    7617    +288     
=======================================
+ Hits        5822    6064    +242     
- Misses      1507    1553     +46     

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[jsuereth]

Going to hold off on this PR for a few revamps.

Ideas:

• Move from <!-- semconv {group}({attributes}) --> to <!-- weaver {jq_expr} {template_file} --> for more flexibility
• Default to refinements to simplify 90% of usage.
• JQ helper functions to create namespaces for attributes.
• Snippets to support namespaces.

[jsuereth]

@lmolkova PTAL at this again - I was able to implement the JQ idea I mentioned.