Update installation information to reflect 4.0 vs. 3.10 and package name change (#3649)

* Update meta.yaml to rename conda package to isis from isis3

* Initial update to install docs to reflect install guide changes with the 3.10 and 4.0 split and the change in the package name

* Update readme to newer installation instructions based on what we decided to do for the builds.

* Update install docs to fix formatting

* Add badge for isis package