DOC: peers: indicate that some server settings are not usable

Let's make it clear in the peers documentation that not all server
parameters may be used, as there is some confusion around this, and
the doc was even misleading by saying that all parameters were
supported.

This should address github issue #919.

(cherry picked from commit 0f4a02b81a509fe0eb13b1455c0b39fa06c92449)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 46ce3a85a814d6bc6f70bb3076350a70a9e1a6ff)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index c2e8023..0e58e01 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -2988,9 +2988,10 @@
   Arguments:
     <param*>  is a list of parameters for this server. The "default-server"
               keyword accepts an important number of options and has a complete
-              section dedicated to it. Please refer to section 5 for more
-              details.
-
+              section dedicated to it. In a peers section, the transport
+              parameters of a "default-server" line are supported. Please refer
+              to section 5 for more details, and the "server" keyword below in
+              this section for some of the restrictions.
 
   See also: "server" and section 5 about server options
 
@@ -3029,12 +3030,16 @@
 
 server <peername> [<ip>:<port>] [param*]
   As previously mentioned, "peer" keyword may be replaced by "server" keyword
-  with a support for all "server" parameters found in 5.2 paragraph.
-  If the underlying peer is local, <ip>:<port> parameters must not be present.
-  These parameters must  be provided on a "bind" line (see "bind" keyword
-  of this "peers" section).
-  Some of these parameters are irrelevant for "peers" sections.
+  with a support for all "server" parameters found in 5.2 paragraph that are
+  related to transport settings. If the underlying peer is local, <ip>:<port>
+  parameters must not be present; these parameters must be provided on a "bind"
+  line (see "bind" keyword of this "peers" section).
 
+  A number of "server" parameters are irrelevant for "peers" sections. Peers by
+  nature do not support dynamic host name resolution nor health checks, hence
+  parameters like "init_addr", "resolvers", "check", "agent-check", or "track"
+  are not supported. Similarly, there is no load balancing nor stickiness, thus
+  parameters such as "weight" or "cookie" have no effect.
 
   Example:
     # The old way.