Explanation
The terraform taint command manually marks a Terraform-managed resource as tainted, forcing it to be destroyed and recreated on the next apply.
This command will not modify infrastructure, but does modify the state file in order to mark a resource as tainted. Once a resource is marked as tainted, the next plan will show that the resource will be destroyed and recreated and the next apply will implement this change.
Forcing the recreation of a resource is useful when you want a certain side effect of recreation that is not visible in the attributes of a resource. For example: re-running provisioners will cause the node to be different or rebooting the machine from a base image will cause new startup scripts to run.
Note that tainting a resource for recreation may affect resources that depend on the newly tainted resource. For example, a DNS resource that uses the IP address of a server may need to be modified to reflect the potentially new IP address of a tainted server. The plan command will show this if this is the case.
This example will taint a single resource:
$ terraform taint aws_security_group.allow_all
The resource aws_security_group.allow_all in the module root has been marked as tainted.
https://www.terraform.io/docs/commands/taint.html

Terraform Enterprise runs on Linux instances, and you must prepare a running Linux instance for Terraform Enterprise before running the installer. You will start and manage this instance like any other server.
Terraform Enterprise currently supports running under the following operating systems:
Standalone deployment:
Debian 7.7+
Ubuntu 14.04.5 / 16.04 / 18.04
Red Hat Enterprise Linux 7.4 - 7.8
CentOS 6.x / 7.4 - 7.8
Amazon Linux 2014.03 / 2014.09 / 2015.03 / 2015.09 / 2016.03 / 2016.09 / 2017.03 / 2017.09 / 2018.03 / 2.0 Oracle Linux 7.4 - 7.8
https://www.terraform.io/docs/enterprise/before-installing/index.html

Organizations commonly want to create a strong separation between multiple deployments of the same infrastructure serving different development stages (e.g. staging vs. production) or different internal teams. In this case, the backend used for each deployment often belongs to that deployment, with different credentials and access controls. Named workspaces are not a suitable isolation mechanism for this scenario.
https://www.terraform.io/docs/state/workspaces.html#when-to-use-multiple-workspaces

Explanation
Github is not a supported backend type.
https://www.terraform.io/docs/backends/types/index.html