Add apostrophe in string example

MattBlack85 · olasitarska · commit 72f2143b9e46 · 2014-09-25T10:57:39.000+02:00
diff --git a/python_introduction/README.md b/python_introduction/README.md
@@ -55,6 +55,18 @@ You can also multiply strings with a number:
 
     >>> "Ola" * 3
     'OlaOlaOla'
+    
+If you need to put an apostrophe inside your string, you have two ways to do it.
+
+Using double quotes:
+
+    >>> "Runnin' down the hill"
+    "Runnin' down the hill"
+    
+or escaping apostrophe with a backslash (`\`):
+
+    >>> 'Runnin\' down the hill'
+    "Runnin' down the hill"
 
 Nice, huh? To see your name in uppercase letters, simply type:
 
