Updates documentation to 0.7.0.

docs/types/mapping-types.rst

@@ -42,7 +42,7 @@ contract that returns the value at the specified address.
 
 ::
 
-    pragma solidity >=0.4.0 <0.7.0;
+    pragma solidity >=0.4.0 <0.8.0;
 
     contract MappingExample {
         mapping(address => uint) public balances;
@@ -67,7 +67,7 @@ The example below uses ``_allowances`` to record the amount someone else is allo
 
 ::
 
-    pragma solidity >=0.4.0 <0.7.0;
+    pragma solidity >=0.4.0 <0.8.0;
 
     contract MappingExample {
 
@@ -121,7 +121,7 @@ the ``sum`` function iterates over to sum all the values.
 
 ::
 
-    pragma solidity >=0.5.99 <0.7.0;
+    pragma solidity >=0.5.99 <0.8.0;
 
     struct IndexValue { uint keyIndex; uint value; }
     struct KeyFlag { uint key; bool deleted; }