feat: Quest loading

- Added config::Config::load_quests()
- Added quest::error::QuestError error type
- Updated documentation

src/account/mod.rs

@@ -1,4 +1,4 @@
-//! Module for handling user accounts
+//! User accounts
 
 use serde::{ Serialize, Deserialize };
 
@@ -10,11 +10,11 @@ fn default_id() -> String {
 #[derive(Serialize, Deserialize)]
 pub struct Account {
     
-    /// User id, specific to used service
+    /// User identifier, specific to used service
     #[serde(default = "default_id")]
     pub id: String,
     
-    /// User balance,
+    /// User balance
     #[serde(default)]
     pub balance: u32,