Fix observation methodology to reflect conservative approach

Why is this change being made?

At some point in hb history a typo appears to have introduced confusion around CHER overrides.

The methodology should be that we can go more conservative on our CHER ratings (e.g. from a 2 to a 3) and not less (e.g. from a 3 to a 2). This MR fixes this and makes the numbers offered as examples align with the documented conservative approach.

This MR also adds ability to override overall System Health Rating (SHR) and take a more conservative rating approach similar to CHER overrides since a combination of observations in a system may not necessarily place the SHR into an appropriate category for where the system should sit relative to risk towards the organization and its compliance obligations.

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