Documentation/vm/page_owner.rst: fix unexpected indentation warns

Fix Unexpected indentation warns in page_owner:

  Documentation/vm/page_owner.rst:92: WARNING: Unexpected indentation.
  Documentation/vm/page_owner.rst:96: WARNING: Unexpected indentation.
  Documentation/vm/page_owner.rst:107: WARNING: Unexpected indentation.

Link: https://lkml.kernel.org/r/20211215001929.47866-1-skhan@linuxfoundation.orgSigned-off-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/page_owner.rst

@@ -89,11 +89,11 @@ Usage
 
 	Page allocated via order XXX, ...
 	PFN XXX ...
-	 // Detailed stack
+	// Detailed stack
 
 	Page allocated via order XXX, ...
 	PFN XXX ...
-	 // Detailed stack
+	// Detailed stack
 
    The ``page_owner_sort`` tool ignores ``PFN`` rows, puts the remaining rows
    in buf, uses regexp to extract the page order value, counts the times
@@ -104,7 +104,7 @@ Usage
 
 	XXX times, XXX pages:
 	Page allocated via order XXX, ...
-	 // Detailed stack
+	// Detailed stack
 
    By default, ``page_owner_sort`` is sorted according to the times of buf.
    If you want to sort by the page nums of buf, use the ``-m`` parameter.