Remove 'message' parameter docs from assert.rst

As per:

	https://github.com/pytest-dev/pytest/issues/3974#issuecomment-463462732

Also made the 'match' parameter more prominent

doc/en/assert.rst

@@ -88,23 +88,30 @@ and if you need to have access to the actual exception info you may use::
 the actual exception raised.  The main attributes of interest are
 ``.type``, ``.value`` and ``.traceback``.
 
-.. versionchanged:: 3.0
+You can pass a ``match`` keyword parameter to the context-manager to test
+that a regular expression matches on the string representation of an exception
+(similar to the ``TestCase.assertRaisesRegexp`` method from ``unittest``)::
 
-In the context manager form you may use the keyword argument
-``message`` to specify a custom failure message::
+    import pytest
 
-     >>> with raises(ZeroDivisionError, message="Expecting ZeroDivisionError"):
-     ...     pass
-     ... Failed: Expecting ZeroDivisionError
+    def myfunc():
+        raise ValueError("Exception 123 raised")
 
-If you want to write test code that works on Python 2.4 as well,
-you may also use two other ways to test for an expected exception::
+    def test_match():
+        with pytest.raises(ValueError, match=r'.* 123 .*'):
+            myfunc()
+
+The regexp parameter of the ``match`` method is matched with the ``re.search``
+function, so in the above example ``match='123'`` would have worked as
+well.
+
+There's an alternate form of the ``pytest.raises`` function where you pass
+a function that will be executed with the given ``*args`` and ``**kwargs`` and
+assert that the given exception is raised::
 
     pytest.raises(ExpectedException, func, *args, **kwargs)
 
-which will execute the specified function with args and kwargs and
-assert that the given ``ExpectedException`` is raised.  The reporter will
-provide you with helpful output in case of failures such as *no
+The reporter will provide you with helpful output in case of failures such as *no
 exception* or *wrong exception*.
 
 Note that it is also possible to specify a "raises" argument to
@@ -121,23 +128,6 @@ exceptions your own code is deliberately raising, whereas using
 like documenting unfixed bugs (where the test describes what "should" happen)
 or bugs in dependencies.
 
-Also, the context manager form accepts a ``match`` keyword parameter to test
-that a regular expression matches on the string representation of an exception
-(like the ``TestCase.assertRaisesRegexp`` method from ``unittest``)::
-
-    import pytest
-
-    def myfunc():
-        raise ValueError("Exception 123 raised")
-
-    def test_match():
-        with pytest.raises(ValueError, match=r'.* 123 .*'):
-            myfunc()
-
-The regexp parameter of the ``match`` method is matched with the ``re.search``
-function. So in the above example ``match='123'`` would have worked as
-well.
-
 
 .. _`assertwarns`: