Add info about exporter reviewers to README.md

[pjanotti]

Helping finding reviewers for exporter changes.

/exporter/alibabacloudlogserviceexporter/ @shabicheng
/exporter/awsxrayexporter/ @kbrockhoff @anuraaga
/exporter/azuremonitorexporter/ @pcwiese
/exporter/carbonexporter/ @pjanotti
/exporter/elasticexporter/ @axw
/exporter/honeycombexporter/ @paulosman @lizthegrey
/exporter/jaegerthrifthttpexporter/ @jpkrohling @pavolloffay
/exporter/kinesisexporter/ @owais
/exporter/lightstepexporter/ @austinlparker @jmacd
/exporter/newrelicexporter/ @MrAlias
/exporter/sapmexporter/ @owais @dmitryax
/exporter/sentryexporter/ @AbhiPrasad
/exporter/signalfxexporter/ @pmcollins @asuresh4
/exporter/splunkhecexporter/ @atoulme
/exporter/stackdriverexporter/ @nilebox @james-bebbington

[codecov]

Codecov Report

Merging #776 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #776      +/-   ##
==========================================
+ Coverage   87.80%   87.84%   +0.04%     
==========================================
  Files         217      217              
  Lines       11746    11746              
==========================================
+ Hits        10313    10318       +5     
+ Misses       1086     1082       -4     
+ Partials      347      346       -1     

Flag	Coverage Δ
#integration	69.55% <ø> (ø)
#unit	87.65% <ø> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
receiver/carbonreceiver/transport/tcp_server.go	67.61% <0.00%> (+1.90%)	⬆️
receiver/prometheusexecreceiver/receiver.go	85.29% <0.00%> (+2.20%)	⬆️

---

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[pjanotti]

Unfortunately, this won't work as intended recording the info on the README so approvers and maintainers can quickly find the proper alias to add to reviews.

[axw]

Unfortunately, this won't work as intended recording the info on the README so approvers and maintainers can quickly find the proper alias to add to reviews.

Out of curiosity, why won't it work? Because it'll block regular refactoring and go.mod updates?

[pjanotti]

Out of curiosity, why won't it work? Because it'll block regular refactoring and go.mod updates?

For CODEOWNERS to work every account listed there would need to have write permissions to the repo.