doc: fix formatting of pmreorder man page

This small change unbreaks the whole man page.

doc/pmreorder/pmreorder.1.md

@@ -283,7 +283,9 @@ through the **pmreorder** tool using the `-x` parameter.
 There are two ways to set macro options:
 
 + Using command line interface in format:
-```PMREORDER_MARKER_NAME1=ReorderName1,PMREORDER_MARKER_NAME2=ReorderName2```
+```
+PMREORDER_MARKER_NAME1=ReorderName1,PMREORDER_MARKER_NAME2=ReorderName2
+```
 
 + Using configuration file in .json format:
 ```