[Rd] Minor typo in R-exts

[Josh O'Brien]

Section 1.1.3 of the "R-exts" manual currently refers to "imports or
importFrom directives" where it means to say "import or importFrom
directives". Results of a diff between R-exts.texi at SVN revision
76864 and a corrected version are copied below.



*** R-exts.texi Mon Jul 22 14:41:19 2019
--- R-exts.texi.modified Mon Jul 22 14:45:32 2019
***************
*** 902,904 ****
  @code{library(@var{pkgname})} should be listed in the @samp{Imports} field
! and not in the @samp{Depends} field.  Packages listed in @code{imports}
  or @code{importFrom} directives in the @file{NAMESPACE} file should
--- 902,904 ----
  @code{library(@var{pkgname})} should be listed in the @samp{Imports} field
! and not in the @samp{Depends} field.  Packages listed in @code{import}
  or @code{importFrom} directives in the @file{NAMESPACE} file should