Adds documentation for Solidity source upgrader.

tools/solidityUpgrade/contracts/DocsExamplePass.sol

@@ -0,0 +1,23 @@
+pragma solidity >0.4.23;
+
+contract Updateable {
+    function run() public view returns (bool);
+    function update() public;
+}
+
+contract Upgradable {
+    function run() public view returns (bool);
+    function upgrade();
+}
+
+contract Source is Updateable, Upgradable {
+    function Source() public {}
+
+    function run()
+        public
+        view
+        returns (bool) {}
+
+    function update() {}
+    function upgrade() {}
+}