Updated constructors and pragma solidity lines.

Updated the Inheritance section of the docs in order to correct old constructor formats and update them to the new constructor() format.

docs/contracts.rst

@@ -841,10 +841,10 @@ Details are given in the following example.
 
 ::
 
-    pragma solidity ^0.4.16;
+    pragma solidity ^0.4.22;
 
     contract owned {
-        function owned() { owner = msg.sender; }
+        constructor() { owner = msg.sender; }
         address owner;
     }
 
@@ -875,7 +875,7 @@ Details are given in the following example.
     // also a base class of `mortal`, yet there is only a single
     // instance of `owned` (as for virtual inheritance in C++).
     contract named is owned, mortal {
-        function named(bytes32 name) {
+        constructor(bytes32 name) {
             Config config = Config(0xD5f9D8D94886E70b06E474c3fB14Fd43E2f23970);
             NameReg(config.lookup(1)).register(name);
         }
@@ -913,10 +913,10 @@ Note that above, we call ``mortal.kill()`` to "forward" the
 destruction request. The way this is done is problematic, as
 seen in the following example::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.22;
 
     contract owned {
-        function owned() public { owner = msg.sender; }
+        constructor() public { owner = msg.sender; }
         address owner;
     }
 
@@ -942,10 +942,10 @@ derived override, but this function will bypass
 ``Base1.kill``, basically because it does not even know about
 ``Base1``.  The way around this is to use ``super``::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.22;
 
     contract owned {
-        function owned() public { owner = msg.sender; }
+        constructor() public { owner = msg.sender; }
         address owner;
     }
 
@@ -1033,7 +1033,7 @@ Arguments for Base Constructors
 Derived contracts need to provide all arguments needed for
 the base constructors. This can be done in two ways::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.22;
 
     contract Base {
         uint x;