upgrade instruction from 4.3

Signed-off-by: Sebastien Goasguen <runseb@gmail.com>
split upgrade instruction into multiple files in /upgrade

Signed-off-by: Sebastien Goasguen <runseb@gmail.com>
split rnotes.rst in upgrade dir and remove it. Update Upgrade instruction to 4.4. Fix rst formating

Signed-off-by: Sebastien Goasguen <runseb@gmail.com>
Update Jira issues and fixes

Signed-off-by: Sebastien Goasguen <runseb@gmail.com>
remplace warning to important for consistency: This closes #11

Signed-off-by: Sebastien Goasguen <runseb@gmail.com>