🚑 Changes Currency to ISO4217 Format (#34)

* 📚 Update Readme to reference Currency Config

* 🐛 Update default currency config

* 💥 Add regex to Currency schema

* 🔨 Fixing Regex format

README.md

@@ -139,8 +139,10 @@ Is used for setting the language. Choose between:
 
 ### Option: `currency`
 
-Determines the currency as displayed in the Grocy interface.
-Examples:  `$`, `€`, `£` or `EUR`.
+Determines the currency as displayed in the Grocy interface, specified by the
+ISO4217 three digit currency code.
+
+Examples:  `USD`, `CAD`, `GBP` or `EUR`.
 
 ### Option: `features`
 

grocy/config.json

@@ -30,7 +30,7 @@
   },
   "options": {
     "culture": "en",
-    "currency": "$",
+    "currency": "USD",
     "features": {
       "batteries": true,
       "calendar": true,
@@ -48,7 +48,7 @@
   "schema": {
     "log_level": "match(^(trace|debug|info|notice|warning|error|fatal)$)?",
     "culture": "match(^(da|de|en|en_GB|es|fr|it|nl|no|pl|ru|sv_SE|ta|tr)$)",
-    "currency": "str",
+    "currency": "match(^[A-Z]{3}$)",
     "features": {
       "batteries": "bool",
       "calendar": "bool",