doc: Updates for v1.0 release candidate

Updates to:
  * Changelog page to list new features, components versions and third-party
    Yocto layers revisions
  * In variables.py set "rd_n2_automotive_version" to "v1.0"
  * In variables.py introduce the "linux_version_patch" variables to hold the
    Linux kernel patch version and display it in the appropriate places
  * In variables.py introduce FVP related variables to hold its version and
    download link

Issue-Id: SCM-5314
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Change-Id: I454b7149050c6177ad3dc5bca2f5a13d4242b344