Toggle the `completed` flag for an Install Note

Install notes can be [optionally] associated with an individual milestone (see figure 1).

Milestone-specific notes are imbued with boolean field: completed . New notes are created with a completed value of FALSE. Notes that are incomplete will display in the UI in two different ways.

1. Figure 2 depicts the milestone timeline with 1 incomplete note in the Site Survey Completed milestone.
2. Figure 3 depicts the milestone details modal with an incomplete note.