Features/2151 gauge description

[ryangroth5]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Adds the missing gaugeinfo field back to the flow tab.

• What is the current behavior? (You can also link to an open issue here)

• no gaugeinfo

• What is the new behavior (if this is a feature change)?

• gaugeinfo shows and is editable using the same rules as reach description

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• no

• Other information:

• none

[ryangroth5]

Addresses https://github.com/AmericanWhitewater/wh2o/issues/2037

[ngottlieb]

might be worth @mattanger reviewing this too as I have not looked at the flow tab code before