bug#32473: Broken menu entry in manual, section 4.1

[HiPhish]

I noticed a broken menu entry in the Info version of the Guix manual: the node 
`Defining Packages` (4.1) has an extra space between the last word and the 
closing colons:

        * package Reference ::  The package data type

The standalone Info reader tolerates it, but not the Info.vim reader, which 
considers the space to be part of the target node name. Neither the Texinfo 
manual (section 4.9) nor the Info manual seem to allow for this extra space, 
so it looks like a bug in the manual to me.

PS: I am the author of the Info.vim reader, if that matters.
https://gitlab.com/HiPhish/info.vim