bpf, docs: Fix instruction.rst indentation

The table captions patch corrected indented most tables to work with
the table directive for adding a caption but missed two of them.
Signed-off-by: Dave Thaler <dthaler1968@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240526061815.22497-1-dthaler1968@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Documentation/bpf/standardization/instruction-set.rst

@@ -681,13 +681,13 @@ two complex atomic operations:
 
 .. table:: Complex atomic operations
 
-===========  ================  ===========================
-imm          value             description
-===========  ================  ===========================
-FETCH        0x01              modifier: return old value
-XCHG         0xe0 | FETCH      atomic exchange
-CMPXCHG      0xf0 | FETCH      atomic compare and exchange
-===========  ================  ===========================
+  ===========  ================  ===========================
+  imm          value             description
+  ===========  ================  ===========================
+  FETCH        0x01              modifier: return old value
+  XCHG         0xe0 | FETCH      atomic exchange
+  CMPXCHG      0xf0 | FETCH      atomic compare and exchange
+  ===========  ================  ===========================
 
 The ``FETCH`` modifier is optional for simple atomic operations, and
 always set for the complex atomic operations.  If the ``FETCH`` flag