Clean up naming of old GENTARGETS infrastructure

With the renaming of XXXTARGETS to xxx-package, the names of the
pkg-xxx.mk files is inconsistent, as well as some internal names in
the documentation.  These inconsistencies are cleaned up here.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

 ...kages-autotargets.txt => adding-packages-autotools.txt} |    4 ++--
 ...packages-cmaketargets.txt => adding-packages-cmake.txt} |    4 ++--
 docs/manual/adding-packages-directory.txt                  |   12 ++++++------
 ...packages-gentargets.txt => adding-packages-generic.txt} |    4 ++--
 docs/manual/adding-packages.txt                            |    6 +++---
 package/Makefile.in                                        |    6 +++---
 package/{pkg-autotargets.mk => pkg-autotools.mk}           |    0
 package/{pkg-cmaketargets.mk => pkg-cmake.mk}              |    0
 package/{pkg-gentargets.mk => pkg-generic.mk}              |    0
 9 files changed, 18 insertions(+), 18 deletions(-)
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>