docs: change documentation URL

[confiq]

Which problem is this PR solving?

• The documentation URL. I did grep search on the project to find if there are any more wrong URLs but I could not find.

Short description of the changes

• PR #546 broke URL docs

[codecov]

Codecov Report

Merging #1460 into master will decrease coverage by 0.10%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1460      +/-   ##
==========================================
- Coverage   93.76%   93.66%   -0.11%     
==========================================
  Files         149      138      -11     
  Lines        4525     4180     -345     
  Branches      939      851      -88     
==========================================
- Hits         4243     3915     -328     
+ Misses        282      265      -17     

Impacted Files	Coverage Δ
...lemetry-tracing/src/export/InMemorySpanExporter.ts
packages/opentelemetry-tracing/src/Tracer.ts
...telemetry-tracing/src/export/BatchSpanProcessor.ts
...es/opentelemetry-tracing/src/MultiSpanProcessor.ts
...ges/opentelemetry-tracing/src/NoopSpanProcessor.ts
...elemetry-tracing/src/export/SimpleSpanProcessor.ts
...elemetry-tracing/src/export/ConsoleSpanExporter.ts
packages/opentelemetry-tracing/src/utility.ts
...s/opentelemetry-tracing/src/BasicTracerProvider.ts
packages/opentelemetry-tracing/src/Span.ts
... and 1 more

[mayurkale22]

Thanks for the PR!