[*] update docs for metrics yaml folder configs

[0xgouda]

• add note in docs about yaml folder based configs being read-only
• mention using yaml-folder for metrics configs in docs

[coveralls]

Pull Request Test Coverage Report for Build 17067856327

Details

• 125 of 142 (88.03%) changed or added relevant lines in 2 files are covered.
• 16 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.4%) to 64.416%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/metrics/yaml.go	120	137	87.59%

Files with Coverage Reduction	New Missed Lines	%
internal/cmdopts/cmdconfig.go	2	74.24%
internal/cmdopts/cmdmetric.go	4	92.31%
internal/metrics/yaml.go	10	85.04%

Totals
Change from base Build 17067698965:	0.4%
Covered Lines:	3320
Relevant Lines:	5154

---

💛 - Coveralls

[pashagolub]

Since #891 is rejected this PR should be updated accordingly

[0xgouda]

Since #891 is rejected this PR should be updated accordingly

@pashagolub

The PR has been updated, it now only updates docs for metrics yaml-folder configs, as tests for using yaml folder has already been provided #889

Also noting that the docs mention env vars being usable for sources and metrics yaml setups, this logic is not implemented for metrics yaml configs, but idk if this is an actual bug or there is no need for supporting the use of envs in metrics yaml files and we only need to update the docs to mention that this is sources only feature?.

[pashagolub]

Yeah, I cannot imagine how to use envvar in metric. So it's better to update docs

[0xgouda]

Yeah, I cannot imagine how to use envvar in metric. So it's better to update docs

done.

[pashagolub]

Thanks! Well done!