restart point vs restartpoint in the docs

While doing something else I noticed that we have 25 uses of "restartpoint" and
three "restart point":

$ git grep -i "restartpoint[s]\?[ .,;]" doc/ | wc -l
      25
$ git grep -i "restart point[s]\?[ .,;]" doc/ | wc -l
       3

Any objection to applying the attached to make those three "restartpoint" to
keep the docs consistent?

--
Daniel Gustafsson