fix: fixup aws detector readme

[legendecas]

Which problem is this PR solving?

• the code example in README is not valid.

[codecov]

Codecov Report

Merging #2379 (e2ec6dd) into main (e089984) will increase coverage by 0.41%.
The diff coverage is n/a.

❗ Current head e2ec6dd differs from pull request most recent head 669cf63. Consider uploading reports for the commit 669cf63 to get more accurate results

@@            Coverage Diff             @@
##             main    #2379      +/-   ##
==========================================
+ Coverage   92.36%   92.77%   +0.41%     
==========================================
  Files         128      145      +17     
  Lines        4244     5221     +977     
  Branches      867     1070     +203     
==========================================
+ Hits         3920     4844     +924     
- Misses        324      377      +53     

Impacted Files	Coverage Δ
...ource-detector-aws/src/detectors/AwsEc2Detector.ts	97.91% <ø> (ø)
...emetry-core/src/platform/node/RandomIdGenerator.ts	87.50% <0.00%> (-6.25%)	⬇️
.../opentelemetry-exporter-collector/src/transform.ts	88.69% <0.00%> (ø)
...ry-exporter-collector/src/CollectorExporterBase.ts	92.15% <0.00%> (ø)
...mentation-xml-http-request/src/enums/EventNames.ts	100.00% <0.00%> (ø)
...kages/opentelemetry-web/src/StackContextManager.ts	94.28% <0.00%> (ø)
...-instrumentation-fetch/src/enums/AttributeNames.ts	100.00% <0.00%> (ø)
...kages/opentelemetry-exporter-collector/src/util.ts	100.00% <0.00%> (ø)
...ackages/opentelemetry-web/src/WebTracerProvider.ts	100.00% <0.00%> (ø)
...emetry-instrumentation-xml-http-request/src/xhr.ts	97.58% <0.00%> (ø)
... and 9 more