Documentation: btt: Unwrap bit 31-30 nested table

Bit 31-30 usage table is already formatted as reST simple table, but it
is wrapped in literal code block instead. Unwrap it.

Signed-off-by: Bagas Sanjaya <[e-mail]>
Reviewed-by: Randy Dunlap <[e-mail]>
Tested-by: Randy Dunlap <[e-mail]>
Reviewed-by: Alison Schofield <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Ira Weiny <[e-mail]>

Documentation/driver-api/nvdimm/btt.rst

···
 ======== =============================================================
 Bit      Description
 ======== =============================================================
-31 - 30	 Error and Zero flags - Used in the following way::
+31 - 30	 Error and Zero flags - Used in the following way:
 
 	   == ==  ====================================================
 	   31 30  Description