bpf: typo fix in Documentation/networking/af_xdp.rst

Fix a simple typo: Completetion -> Completion
Signed-off-by: Konrad Djimeli <kdjimeli@igalia.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Documentation/networking/af_xdp.rst

@@ -159,8 +159,8 @@ log2(2048) LSB of the addr will be masked off, meaning that 2048, 2050
 and 3000 refers to the same chunk.
 
 
-UMEM Completetion Ring
-~~~~~~~~~~~~~~~~~~~~~~
+UMEM Completion Ring
+~~~~~~~~~~~~~~~~~~~~
 
 The Completion Ring is used transfer ownership of UMEM frames from
 kernel-space to user-space. Just like the Fill ring, UMEM indicies are