Add stockprice variable documentation (#4)

Author: styler

docs/chatbot/variables/stockprice.md

@@ -0,0 +1,26 @@
+---
+id: stockprice
+tags:
+  - chatbot
+  - variable
+---
+
+# $(stockprice)
+
+Displays the current stock price of a given stock symbol.
+
+#### Parameters
+
+You must specify the stock symbol to display the price of.
+
+#### Example Input
+
+```
+${stockprice AAPL} 
+```
+
+#### Example Output
+
+```
+173.93
+```