qemu-options: Move -iscsi under "Block device options"

-iscsi ended up under the "Device URL Syntax" heading by a sequence of
errors, as explained in the previous commit.  Move it under the "Block
device options" heading.  Nothing left under "Device URL Syntax";
drop the heading.

Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20171002140307.5292-5-armbru@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NRonnie Sahlberg <ronniesahlberg@gmail.com>

qemu-options.hx

@@ -1182,6 +1182,13 @@ STEXI
 Create synthetic file system image
 ETEXI
 
+DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
+    "-iscsi [user=user][,password=password]\n"
+    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
+    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
+    "       [,timeout=timeout]\n"
+    "                iSCSI session parameters\n", QEMU_ARCH_ALL)
+
 STEXI
 @end table
 ETEXI
@@ -2821,14 +2828,6 @@ STEXI
 ETEXI
 DEFHEADING()
 
-DEFHEADING(Device URL Syntax:)
-DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
-    "-iscsi [user=user][,password=password]\n"
-    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
-    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
-    "       [,timeout=timeout]\n"
-    "                iSCSI session parameters\n", QEMU_ARCH_ALL)
-
 DEFHEADING(Bluetooth(R) options:)
 STEXI
 @table @option