docs: add dynamic badge

[bmorelli25]

What does this pull request do?

1. This PR adds the Dynamic badge to supported configurations:

• capture_body
• TransactionSampleRate
• TransactionMaxSpans

2. It adds a commented out Dynamic badge to pending (New central config options: CaptureHeaders, LogLevel, SpanFramesMinDuration, StackTraceLimit #794) configurations:

• capture_headers
• log_level
• span_frames_min_duration
• stack_trace_limit

3. This PR adds a section on Dynamic configuration.

Open questions:

• CaptureBodyContentTypes shows as reloadable, but it isn't supported in the APM app. See: https://github.com/elastic/kibana/blob/master/x-pack/plugins/apm/common/agent_configuration/setting_definitions/general_settings.ts. How should we mark this config?
• What do you think of this approach for documenting this feature?

Documentation preview

http://apm-agent-dotnet_813.docs-preview.app.elstc.co/diff

Related issues

For elastic/apm#232
For https://github.com/elastic/observability-dev/issues/639

[bmorelli25]

Sorry about all of these. Just updated my formatting rules. I can remove them from this PR if you'd like.

[gregkalapos]

No worries, all valid changes - feel free to keep those.

[gregkalapos]

Looks very nice! 👏

To the questions:

CaptureBodyContentTypes

Will we still offer a text field in Kibana to put in any config name for central config? If yes, I think we can mark it as dynamic, otherwise I’d just not mark it as dynamic and we can follow up later on this.

What do you think of this approach for documenting this feature?

I like it a lot. It’s way easier to spot which ones are dynamic 👍

[gregkalapos]

@v1v just a nit here following up on #793 - in this "doc-only PR" the whole repo gets built still because there is a new .svg file. I feel we'll survive this :) just saying in case you want to reiterate on that.

[codecov-io]

Codecov Report

Merging #813 into master will increase coverage by 0.91%.
The diff coverage is 85.00%.

@@            Coverage Diff             @@
##           master     #813      +/-   ##
==========================================
+ Coverage   80.44%   81.36%   +0.91%     
==========================================
  Files         114      114              
  Lines        5379     5542     +163     
==========================================
+ Hits         4327     4509     +182     
+ Misses       1052     1033      -19     

Impacted Files	Coverage Δ
...c/Elastic.Apm.NetCoreAll/ApmMiddlewareExtension.cs	0.00% <0.00%> (ø)
src/Elastic.Apm/Model/Transaction.cs	99.47% <94.44%> (ø)
src/Elastic.Apm/Agent.cs	68.08% <0.00%> (-17.63%)	⬇️
src/Elastic.Apm/Model/Span.cs	99.59% <0.00%> (+0.73%)	⬆️
src/Elastic.Apm/Helpers/SystemInfoHelper.cs	81.42% <0.00%> (+1.42%)	⬆️
src/Elastic.Apm/Metrics/MetricsCollector.cs	88.73% <0.00%> (+2.11%)	⬆️
...c.Apm/Metrics/MetricsProvider/GcMetricsProvider.cs	63.74% <0.00%> (+2.33%)	⬆️
src/Elastic.Apm/Helpers/AgentTimer.cs	83.33% <0.00%> (+5.55%)	⬆️
src/Elastic.Apm/Report/PayloadSenderV2.cs	86.95% <0.00%> (+8.47%)	⬆️
... and 1 more

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[bmorelli25]

Awesome! If it's alright, I'll wait until tomorrow to merge this. I'm using this PR and a similar one in the Python repository for feedback on this documentation approach before applying it to all Agents.

Will we still offer a text field in Kibana to put in any config name for central config?

No, only the seven configurations listed in the description will be configurable. Sounds good. I'll leave it unmarked for now.

[gregkalapos]

I should have not talked about the CI on this PR...

The last build reached time-out (1 hour - it was already almost done) 😱 - I have never seen that (currently it takes around 55mins usually - 25 from that is just installing tools). Re-triggered.

[v1v]

@v1v just a nit here following up on #793 - in this "doc-only PR" the whole repo gets built still because there is a new .svg file. I feel we'll survive this :) just saying in case you want to reiterate on that.

#817

should help