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

2e85840 [RELEASE] Released version 1.5-dev26
Updating HAProxy stable documentation v1.5-dev26 generated by haproxy-dconv v0.3.1-19

2e85840 [RELEASE] Released version 1.5-dev26
2705a61 DOC: document the workarouds for Google Chrome's bogus pre-connect
81f5d94 MAJOR: agent: rework the response processing and support additional actions
9b5aecd MEDIUM: cli: add support for enabling/disabling health checks.
2a4b70f MINOR: cli: introduce a new "set server" command
3209123 MEDIUM: server: allow multi-level server tracking
bef1b32 MINOR: checks: simplify and improve reporting of state changes when using log-health-checks
2a06e39 DOC: Add some precisions about acl default matching method