Update userguide for add and delete insurance

[matthewyip1511]

Updating the user guide to reflect the features for addInsurance and deleteInsurance that we have built 🙂

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Files with missing lines	Coverage Δ	Complexity Δ
...ess/logic/parser/DeleteInsuranceCommandParser.java	63.63% <ø> (ø)	2.00 <0.00> (ø)