DOC: configuration: remove wrong tcp-request examples in tcp-response

There is a massive abuse of copy-paste in the doc that is visible in
the examples and arguments declaration. Let's at least remove irrelevant
examples for now.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 987ea45..59bf557 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -12587,7 +12587,7 @@
         set-tos".
 
     - set-var(<var-name>) <expr>
-        Sets a variable.
+        Sets a variable from an expression.
 
     - unset-var(<var-name>)
         Unsets a variable.
@@ -12681,17 +12681,9 @@
     <expr>     Is a standard HAProxy expression formed by a sample-fetch
                followed by some converters.
 
-  Example:
-
-        tcp-request content set-var(sess.my_var) src
-
   The "unset-var" is used to unset a variable. See above for details about
   <var-name>.
 
-  Example:
-
-        tcp-request content unset-var(sess.my_var)
-
   The "send-spoe-group" is used to trigger sending of a group of SPOE
   messages. To do so, the SPOE engine used to send messages must be defined, as
   well as the SPOE group to send. Of course, the SPOE engine must refer to an