Updating redis instrumentation to use instrumentor interface

[codeboten]

Currently the redis instrumentation documents using the patch interface directly, this should be updated once this issue is resolved: open-telemetry/opentelemetry-python#554

Here's documentation:
https://github.com/open-telemetry/opentelemetry-python-contrib/pull/21/files/676c3499819fcab55d0de47c7ef8555f81bb0894#diff-a42497cde4dba9f19c87f87a001c4cc8R28

[mauriciovasquezbernal]

Solved by open-telemetry/opentelemetry-python#595.