Update index.rst
Merge pull request #21 from AnaFdez/patch-1

Admin manual (es): update index.rst
Update migration.rst

Added TIP for sync_maildirs.sh
Admin manual (es): update translation
Merge branch 'master' of https://github.com/nethesis/nethserver-docs

Conflicts:
	administrator-manual/es/index.rst
Merge branch 'master' of https://github.com/AnaFdez/nethserver-docs

Conflicts:
	administrator-manual/es/accounts.rst
	administrator-manual/es/fax_server.rst
	administrator-manual/es/ups.rst