doc: fix grammar and parameters in l2fwd-crypto guide

doc: fix grammar and parameters in l2fwd-crypto guide

Doc was updated with fixed grammar in most cases. These
include adding periods to ends of sentences and capitalizing
some words. Some instances of "a" were changed to "an". The
option "-n 4" has also been removed from the example of
running the application.

Fixes: ba7b86b1419 ("doc: add l2fwd-crypto sample app guide")
Fixes: 2661f4fbe93 ("examples/l2fwd-crypto: add AEAD parameters")
Fixes: 4790f99d2d3 ("examples/l2fwd-crypto: use cryptodev algorithm parser")
Fixes: 5949e30dae6 ("doc: fix typo in l2fwd-crypto usage")
Fixes: acf8616901b ("cryptodev: add auth IV")
Fixes: b79e4c00af0 ("cryptodev: use AES-GCM/CCM as AEAD algorithms")
Fixes: d2797f51cc6 ("examples/l2fwd-crypto: add cryptodev mask option")
Fixes: e2a94f9ad3e ("doc: remove references to make from apps guide")
Fixes: 10b9d471a6f ("doc: update minimum requirement of l2fwd-crypto")
Fixes: 3cc28001a33 ("doc: fix typo in l2fwd-crypto guide")
Cc: stable@dpdk.org
Signed-off-by: Jakub Poczatek <jakub.poczatek@intel.com>
Acked-by: Akhil Goyal <gakhil@marvell.com>