Fixing warning in command SubtractAssetQuantity, removing unnecessarily includes, small documentation change #3150

Job	Run time
Pull requests from forks should use other workflow	2s
pr_comment_reaction_rocket	0s
Check if github workflows were properly made from sources	16s
generate_matrixes	7s
prepare-macos-env	5s
Docker-iroha-builder	3m 35s
prepare-windows-env	2s
build-W	0s
build-M (macos clang Debug normal)	1h 15m 40s
build-UR (ubuntu gcc-10 Release normal)	48m 47s
build-UD (ubuntu gcc-10 Debug normal)	57m 34s
docker-R	0s
docker-D	0s
	3h 6m 8s

Provide feedback