Add plotconfig as property documentation and sample

freqtrade/templates/subtemplates/plot_config_full.j2

@@ -1,18 +1,20 @@
 
-plot_config = {
-    # Main plot indicators (Moving averages, ...)
-    'main_plot': {
-        'tema': {},
-        'sar': {'color': 'white'},
-    },
-    'subplots': {
-        # Subplots - each dict defines one additional plot
-        "MACD": {
-            'macd': {'color': 'blue'},
-            'macdsignal': {'color': 'orange'},
+@property
+def plot_config(self):
+    return {
+        # Main plot indicators (Moving averages, ...)
+        'main_plot': {
+            'tema': {},
+            'sar': {'color': 'white'},
         },
-        "RSI": {
-            'rsi': {'color': 'red'},
+        'subplots': {
+            # Subplots - each dict defines one additional plot
+            "MACD": {
+                'macd': {'color': 'blue'},
+                'macdsignal': {'color': 'orange'},
+            },
+            "RSI": {
+                'rsi': {'color': 'red'},
+            }
         }
     }
-}