Since this extension is fairly new for almost all the contributors, remembering
the admonition (with titles) is difficult. The list (-l) flag provides
a list of all the active admonitions along with titles.
For usage, hg releasenotes -l returns the list.
Generally we add a '_' before an internal function. Since you need to resend because you need to rebase, can you change the function name to _getadmonitionlist. Also it will be extremely great if you send a patch documenting the functions in the releasenotes.py file.