Added missing-raises-doc message example (#6341)

Co-authored-by: Daniël van Noord <13665637+DanielNoord@users.noreply.github.com>

doc/data/messages/m/missing-raises-doc/bad.py

@@ -0,0 +1,8 @@
+def integer_sum(a: int, b: int):  # [missing-raises-doc]
+    """Returns sum of two integers
+    :param a: first integer
+    :param b: second integer
+    """
+    if not (isinstance(a, int) and isinstance(b, int)):
+        raise ValueError('Function supports only integer parameters.')
+    return a + b

doc/data/messages/m/missing-raises-doc/good.py

@@ -0,0 +1,9 @@
+def integer_sum(a: int, b: int):
+    """Returns sum of two integers
+    :param a: first integer
+    :param b: second integer
+    :raises ValueError: One of the parameters is not an integer.
+    """
+    if not (isinstance(a, int) and isinstance(b, int)):
+        raise ValueError('Function supports only integer parameters.')
+    return a + b