releasenotes: add check flag for use of admonitions and its validity
While using releasenotes extension, we will be using admonitions in commit messages.
The check (-c) flag will look for an admonition within the message. If it exists, it will
verify if it is stated under default or custom admonition. The check fails if the
admonition is not present in any of them. It also suggests similar admonitions
in case the admonition is invalid.
Differential Revision: https://phab.mercurial-scm.org/D368
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}