tiny correction to NR

[Vicente Solsona]

hello,

the example in the third entry of NR "4.6.2 Changing spacing" is inaccurate
afaik:

---------8<---------------------

e4 c g\f c
\override DynamicText #'extra-offset = #'( -2.2 . 2.0)
e4 c g\f c

---------8<---------------------

#'extra-offset does *not* affect vertical nor horizontal spacing, so it
does not save vertical space. we have to disable the collision first so
the dynamics don't take vertical space and then move it for aesthetical
purposes, so the valid example should be (after a native english revision):

---------8<---------------------

e4 c g\f c
\override DynamicLineSpanner #'outside-staff-priority = ##f % make  
dynamics not to take vertical space
\override DynamicText #'extra-offset = #'(-2.2 . 2.2) % place the dynamics  
manually to improve appearance
e4 c g\f c

---------8<---------------------

greetings,

Vicente

side note: why \once doesn't work in the previous example (in 2.12.3)?