Fix missing AWS EC2 instance types

[beiermi]

General information

The Amazon Web Services (AWS) cloud agent in checkmk fails to recognize newer EC2 instance types.
This is fixed by adding the newer EC2 instance types.

Bug reports

Please include:

• Your operating system name and version
• Any details about your local setup that might be helpful in troubleshooting
• Detailed steps to reproduce the bug
• An agent output or SNMP walk
• The ID of a submitted crash report for reference (if applicable)

Proposed changes

• What is the expected behavior?
  Monitoring an AWS Account running e.g. r6i.2xlarge instances is working.
• What is the observed behavior?
  Monitoring an AWS Account running e.g. r6i.2xlarge instances produces an error message:

Unknown resource running_ondemand_instances_r6i.2xlarge(!).