docs: create a getting started guide

[dyladan]

Which problem is this PR solving?

• Create a getting started guide #416

What have you done

Tracing

• zipkin setup
• configure tracing
• export traces

Metrics

• prometheus setup
• configure metrics collection
• export metrics

See the guide in its current form here https://github.com/dynatrace-oss-contrib/opentelemetry-js/blob/getting-started/getting-started/Getting-Started.md

[codecov-io]

Codecov Report

Merging #566 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #566      +/-   ##
==========================================
- Coverage   90.12%   90.12%   -0.01%     
==========================================
  Files         150      149       -1     
  Lines        7381     7400      +19     
  Branches      667      669       +2     
==========================================
+ Hits         6652     6669      +17     
- Misses        729      731       +2

Impacted Files	Coverage Δ
...kages/opentelemetry-plugin-dns/test/utils/utils.ts	33.33% <0%> (-26.67%)	⬇️
...ry-scope-async-hooks/src/AsyncHooksScopeManager.ts	97.67% <0%> (ø)	⬆️
packages/opentelemetry-tracing/src/BasicTracer.ts	100% <0%> (ø)	⬆️
...elemetry-tracing/src/export/ConsoleSpanExporter.ts	85.71% <0%> (ø)	⬆️
...es/opentelemetry-node/src/instrumentation/utils.ts	90.47% <0%> (-9.53%)	⬇️
...es/opentelemetry-plugin-document-load/src/utils.ts	100% <0%> (ø)	⬆️
packages/opentelemetry-tracing/src/Span.ts	100% <0%> (ø)	⬆️
packages/opentelemetry-metrics/src/Utils.ts	100% <0%> (ø)	⬆️
...res/opentelemetry-plugin-pg/test/assertionUtils.ts	96.29% <0%> (-3.71%)	⬇️
...y-plugin-document-load/src/enums/AttributeNames.ts	100% <0%> (ø)	⬆️
... and 50 more

[mayurkale22]

Overall lgtm

[mayurkale22]

LGTM, added 2 minor comments