Spelling, grammar, and typo cleanup

doc/man/knot.conf.5in

doc/reference.rst

src/dnssec/doc/coding.md

src/dnssec/lib/dnssec/keystore.h

src/dnssec/lib/error.c

src/dnssec/lib/kasp/dir/json.c

src/knot/nameserver/nsec_proofs.c

src/knot/zone/zone-dump.c

src/libknot/rrtype/opt.h

src/libknot/tsig-op.h

src/utils/common/exec.c

src/utils/common/params.h

src/utils/keymgr/cmdparse/parameter.c

src/utils/kzonecheck/main.c

src/zscanner/scanner.h

tests-extra/tests/axfr/failover/test.py

tests-extra/tests/modules/rosedb/test.py