Revert "qemu-img: Document copy offloading implications with -S and -c"

This reverts commit eb461485f4558e362fab905735b50987505bca44.

Now that we introduce an explicit option, these implicit rules are not
used.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qemu-img.texi b/qemu-img.texi
index 5853cd1..aeb1b9e 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -96,8 +96,7 @@
 below for further description.
 
 @item -c
-indicates that target image must be compressed (qcow format only). If this
-option is used, copy offloading will not be attempted.
+indicates that target image must be compressed (qcow format only)
 
 @item -h
 with or without a command shows help and lists the supported formats
@@ -116,8 +115,7 @@
 indicates the consecutive number of bytes that must contain only zeros
 for qemu-img to create a sparse image during conversion. This value is rounded
 down to the nearest 512 bytes. You may use the common size suffixes like
-@code{k} for kilobytes. If this option is used, copy offloading will not be
-attempted.
+@code{k} for kilobytes.
 
 @item -t @var{cache}
 specifies the cache mode that should be used with the (destination) file. See