Fix typo in the "is" example of README
@@ -102,7 +102,7 @@ of those comparisons is implementation specific (due to common object caching).
```python
x is 5 # x == 5
x is not 5 # x != 5
-x is 'foo' # x == foo
+x is 'foo' # x == 'foo'
```
### `ur` string literals
