Fix quoting around "IBM" in the SDL sample

ehudon · bbakerman · commit c5b129f9f4db · 2018-07-27T17:35:56.000+10:00
diff --git a/docs/subscriptions.rst b/docs/subscriptions.rst
@@ -16,7 +16,7 @@ Imagine you have an stock market pricing service and you make a graphql subscrip
 .. code-block:: graphql
 
     subscription StockCodeSubscription {
-        stockQuotes(stockCode:"IBM') {
+        stockQuotes(stockCode:"IBM") {
             dateTime
             stockCode
             stockPrice
