docs: fix syntax error in wait_chain docstring example (#548)

Add missing closing bracket in the wait_chain docstring example code. Also fix the multi-line string in the print statement.

Closes #250

Author: VedantMadane

tenacity/wait.py

@@ -98,10 +98,10 @@ class wait_chain(wait_base):
 
         @retry(wait=wait_chain(*[wait_fixed(1) for i in range(3)] +
                                [wait_fixed(2) for j in range(5)] +
-                               [wait_fixed(5) for k in range(4)))
+                               [wait_fixed(5) for k in range(4)]))
         def wait_chained():
-            print("Wait 1s for 3 attempts, 2s for 5 attempts and 5s
-                   thereafter.")
+            print("Wait 1s for 3 attempts, 2s for 5 attempts and 5s "
+                  "thereafter.")
     """
 
     def __init__(self, *strategies: wait_base) -> None: