docs: update trace filter docs (#12147)

Resolves: #12141

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

docs/advanced_usage.rst

@@ -342,11 +342,7 @@ all traces of incoming requests to a specific url::
                     return None
             return trace
 
-    tracer.configure(settings={
-        'FILTERS': [
-            FilterbyName(),
-        ],
-    })
+    tracer.configure(trace_processors=[FilterbyName()])
 
 The filters in the filters list will be applied sequentially to each trace
 and the resulting trace will either be sent to the Agent or discarded.
@@ -367,7 +363,7 @@ the pipeline or ``None`` if the trace should be discarded::
             ...
 
     # And then configure it with
-    tracer.configure(settings={'FILTERS': [FilterExample()]})
+    tracer.configure(trace_processors=[FilterExample()])
 
 (see filters.py for other example implementations)
 

docs/troubleshooting.rst

@@ -91,7 +91,7 @@ While this is default behavior for integrations, users can add a trace filter to
         return trace
 
 
-  tracer.configure(settings={'FILTERS': [ErrorFilter()]})
+  tracer.configure(trace_processors=[ErrorFilter()])