[DOC] fixed 2 typos in haproxy-en/fr

-st was indicated instead of -sf, and the pidfile was wrong.
diff --git a/doc/haproxy-en.txt b/doc/haproxy-en.txt
index 50a4802..d18f59a 100644
--- a/doc/haproxy-en.txt
+++ b/doc/haproxy-en.txt
@@ -322,7 +322,7 @@
 
     # to reload a new configuration with minimal service impact and without
     # breaking existing sessions :
-    # haproxy -f haproxy.cfg -p $(</var/run/haproxy-private.pid) -st $(</var/run/haproxy-private.pid)
+    # haproxy -f haproxy.cfg -p /var/run/haproxy-private.pid -sf $(</var/run/haproxy-private.pid)
 
 1.7) Polling mechanisms
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