docs and typos

docs/international.md

@@ -1,6 +1,6 @@
 # International Keycodes
-International extention adds keys for non US layouts. It can simply be added to 
-the extentions list.
+International extension adds keys for non US layouts. It can simply be added to 
+the extensions list.
 
 ```python
 from kmk.extensions.international import International