Complete documentation with missing description of newly added columns.
This should be backported up to 2.4
97. used_conn_cur [...S]: current number of connections in use
98. need_conn_est [...S]: estimated needed number of connections
99. uweight [..BS]: total user weight (backend), server user weight (server)
+ 100. agg_server_status [..B.]: backend aggregated gauge of server's status
+ 101. agg_server_status_check [..B.]: (deprecated)
+ 102. agg_check_status [..B.]: backend aggregated gauge of server's state check
+ status
For all other statistics domains, the presence or the order of the fields are
not guaranteed. In this case, the header line should always be used to parse