minirst: dynamically compile admonitions regexp Currently, parsing admonitions uses a static regular expression created from a pre-defined list of admonitions. A future patch will introduce a feature that needs to parse custom admonitions. Prepare for this by compiling the admonitions regular expression during each function invocation. Strictly speaking, there is a slight performance loss here. But we only run this code as part of displaying help text. I don't think the loss will be noticeable and I don't think we care if it were.