The trace2 output, when sending them to files in a designated
directory, can populate the directory with too many files; a
mechanism is introduced to set the maximum number of files and
discard further logs when the maximum is reached.
* js/trace2-cap-max-output-files:
trace2: write discard message to sentinel files
trace2: discard new traces if target directory has too many files
docs: clarify trace2 version invariants
docs: mention trace2 target-dir mode in git-config
d0ce4d9024