Add descriptions

Signed-off-by: GitHub <noreply@github.com>

Author: ryanlua

docs/api-reference.md

@@ -6,44 +6,60 @@
 getEnabled(): boolean
 ```
 
+Gets if the backpack is enabled.
+
 ### setEnabled
 
 ```
 setEnabled(enabled: boolean): ()
 ```
 
+Sets whether the backpack is enabled or not.
+
 ### getTheme
 
 ```
 getTheme(): StyleSheet
 ```
 
+Gets the active StyleSheet for the backpack theme.
+
 ### setTheme
 
 ```
 setTheme(theme: "DefaultTheme" | "LegacyTheme" | StyleSheet): ()
 ```
 
+Configures the backpack theme with a StyleSheet.
+
 ### getTopbarIcon
 
 ```
 getTopbarIcon(): TopbarPlus.Icon
 ```
 
+Gets the TopbarPlus icon used to toggle the backpack.
+
 ### openInventory
 
 ```
 openInventory(): ()
 ```
 
+Opens the inventory.
+
 ### closeInventory
 
 ```
 closeInventory(): ()
 ```
 
+Closes the inventory.
+
 ### isInventoryOpen
 
 ```
 isInventoryOpen(): boolean
 ```
+
+Returns `true` if the inventory is open.