terminology.rst: fixed grammer issues
terminology.rst: fixed grammer issues

conorsch/securedrop,heartsucker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,conorsch/securedrop