docs(instrumentation-redis): add instrumentation options

[unflxw]

Which problem is this PR solving?

The Redis instrumentation already accepts several options on initialisation, in a similar manner to the IORedis instrumentation. Unlike in the IORedis instrumentation, however, these options are undocumented for the Redis instrumentation. This PR copies the relevant documentation about initialisation options from the IORedis instrumentation's README to the Redis one, tweaking it where the instrumentation libraries differ.

Short description of the changes

• Copy documentation on IORedis instrumentation's initialisation options to the Redis instrumentation's README.
• Do not copy any documentation relating to the requestHook option, as it is not supported by the Redis instrumentation.
• Amend the documentation to document differences in default values:
  • In the IORedis instrumentation, the default db.statement serialiser returns the command name and arguments concatenated by spaces. The Redis instrumentation returns only the command name. The examples given for custom db.statement serialiser functions on each library's README correspond to the other library's default db.statement serialiser.
  • In the IORedis instrumentation, the default value for requireParentSpan is true. In the Redis instrumentation, it is false.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: unflxw / name: Noemi (fed7e38)

[codecov]

Codecov Report

Merging #1029 (fed7e38) into main (116caab) will decrease coverage by 0.17%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1029      +/-   ##
==========================================
- Coverage   95.91%   95.73%   -0.18%     
==========================================
  Files          13       16       +3     
  Lines         856     1008     +152     
  Branches      178      198      +20     
==========================================
+ Hits          821      965     +144     
- Misses         35       43       +8     

Impacted Files	Coverage Δ
...tapackages/auto-instrumentations-node/src/utils.ts	97.91% <0.00%> (ø)
...metry-instrumentation-redis/src/instrumentation.ts	93.47% <0.00%> (ø)
...e/opentelemetry-instrumentation-redis/src/utils.ts	93.10% <0.00%> (ø)