DOC: configuration: place the HAPROXY_HTTP_LOG_FMT example on the correct line

When HAPROXY_HTTP_LOG_FMT was added by commit 537b9e7f36 ("MINOR: config:
add environment variables for default log format"), the example was placed
by accident after the clf log format instead of the HTTP log format,
causing a bit of confusion.

This can be backported to 2.8.

(cherry picked from commit c22fc591d428c55d76b2e18799fca804fafaf558)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit ef35df8349544484a00eba1217a23646e6138891)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit eee0037285a023624f59d3ba306113a02c5bfa3f)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index cffc03f..d2b4f1f 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -23133,6 +23133,8 @@
     # strict equivalent of "option httplog"
     log-format "%ci:%cp [%tr] %ft %b/%s %TR/%Tw/%Tc/%Tr/%Ta %ST %B %CC \
                 %CS %tsc %ac/%fc/%bc/%sc/%rc %sq/%bq %hr %hs %{+Q}r"
+    # or using the HAPROXY_HTTP_LOG_FMT variable
+    log-format "${HAPROXY_HTTP_LOG_FMT}"
 
 And the CLF log format is internally declared as a custom log format based on
 this exact string:
@@ -23141,8 +23143,6 @@
     log-format "%{+Q}o %{-Q}ci - - [%trg] %r %ST %B \"\" \"\" %cp \
                 %ms %ft %b %s %TR %Tw %Tc %Tr %Ta %tsc %ac %fc \
                 %bc %sc %rc %sq %bq %CC %CS %hrl %hsl"
-    # or using the HAPROXY_HTTP_LOG_FMT variable
-    log-format "${HAPROXY_HTTP_LOG_FMT}"
 
 Most fields are shared with the TCP log, some being different. A few fields may
 slightly vary depending on some configuration options. Those ones are marked