docs: fix simple typo, expressons -> expressions
docs: fix simple typo, expressons -> expressions

There is a small typo in kivy/lang/__init__.py.

Should read `expressions` rather than `expressons`.

matham/kivy,akshayaurora/kivy,kivy/kivy,akshayaurora/kivy,rnixx/kivy,akshayaurora/kivy,matham/kivy,kivy/kivy,rnixx/kivy,matham/kivy,rnixx/kivy,kivy/kivy,matham/kivy