DOC: management: document reuse and connect counters in the CSV format

Counters for connect and reuse were added in the stats with commit
f1573848 ("MINOR: backend: count the number of connect and reuse
per server and per backend") but not documented the CSV format in
management.txt

(cherry picked from commit 708eb88845bf6a772e5adfdf9fd660a2b7c89636)
Signed-off-by: Willy Tarreau <w@1wt.eu>
1 file changed