Fix Nubia's devices commands that contains underscore

Change-Id: Ib53da15f227ac09e39d2de297de3c2a53c31d6d9
diff --git a/_nubia/nubianx563j.markdown b/_nubia/nubianx563j.markdown
index 02df8f3..42d1362 100644
--- a/_nubia/nubianx563j.markdown
+++ b/_nubia/nubianx563j.markdown
@@ -23,6 +23,6 @@
 
 unlock bootloader and flash twrp
 
-fastboot oem nubia_unlock NUBIA_NX563J
+<p class="code">fastboot oem nubia_unlock NUBIA_NX563J</p>
 
-fastboot flash recovery twrp.img
+<p class="code">fastboot flash recovery twrp.img</p>