Troff interprets single quotes at the beginning of lines as control characters.
There is one in the source for mu-labels.1, which results in that line's being
omitted from the output:
The export command takes the labels in the store and the messages they
apply to, and writes this information to a file. You can import this
file later, to restore the labels. The command takes a path to a file or
a directory (ending in
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
