Merge pull request nus-cs2103-AY2021S1#85 from yyutong/master

Fix showBudget bug, update UserGuide

Author: tanwayne890

docs/UserGuide.md

@@ -193,6 +193,7 @@ Action | Format, Examples
 **List** | `list`
 **Delete** | `delete INDEX`<br> e.g., `delete 3`
 **View** | `view INDEX`<br> e.g., `view 5`
+**View existing categori labels** | `viewCategory`
 **Add Description** | `addDes INDEX d/DESCRIPTION`<br> e.g., `addDes 2 d/ENTERTAINMENT`
 **Delete Description** | `deleteDes INDEX`<br> e.g., `deleteDes 2`
 **Set Budget** | `setBudget a/AMOUNT`<br> e.g., `setBudget a/1000`

src/main/java/seedu/address/model/person/UniqueExpenseList.java

@@ -160,7 +160,7 @@ public double getBudget() {
 
     public double getRemainingBudget() {
         double used = 0;
-        for (int i = 0; i < internalList.size() - 1; i++) {
+        for (int i = 0; i < internalList.size(); i++) {
             used += internalList.get(i).getAmount().getValue();
         }
         return this.budget - used;