AWS dimension select config issue

[tul]

Something that might be worth making clear in the documentation: the aws dimension select in this tool is called aws_dimensions_select_regex in the config file, whereas in the official Java tool, it's called aws_dimension_select_regex (ie without the "s").

This had me scratching my head for a while when moving a config over from the official exporter to this one.

Also, the aws_dimensions_select_regex in this tool only supports 1 regexp per dimension, whereas the official one supports a list. It might be worth considering adding support for a list of reg exps as a new key called aws_dimension_select_regex and then it would be compatible with the official tool in both key name and format?

You could leave the existing aws_dimensions_select_regex supporting a single regexp for backwards compatibility perhaps.