Removed redundant POST request exclusion info

The default ``ExceptionListener::setTargetPath()`` already excludes POSTs/PUTs, so suggesting that people who implement their own listener to do this is a bit misleading.

However, doing this to prevent XMLHttpRequest URIs from being saved is still valuable.
Improved clarity of explanation around overriding setTargetPath()
Added comma after "For example"
feature #3883 Removed redundant POST request exclusion info (ryancastle)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #3883).

Discussion
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Removed redundant POST request exclusion info

The default ``ExceptionListener::setTargetPath()`` already excludes POSTs/PUTs, so suggesting that people should implement their own listener to do this is a bit misleading.

However, doing this to prevent XMLHttpRequest URIs from being saved is still valuable.

Commits
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01fc656 Added comma after "For example"
c633f6b Improved clarity of explanation around overriding setTargetPath()
556365b Removed redundant POST request exclusion info