Updating HAProxy snapshot documentation v1.5-dev26-38 generated by haproxy-dconv v0.3.1-19

218f064 MEDIUM: http: add actions "replace-header" and "replace-values" in http-req/resp
f5b1cc3 MEDIUM: stats: report per-backend and per-server time stats in HTML and CSV outputs
a28df3e MEDIUM: stats: report the last check and last agent's output on the CSV status
a3310dc DOC: clarify the CSV format