[2.7] Fix typos in multiple `.rst` files (GH-1668) (#1707)

diff --git a/Doc/library/sunau.rst b/Doc/library/sunau.rst
index 5d57d4b..5bf4803 100644
--- a/Doc/library/sunau.rst
+++ b/Doc/library/sunau.rst
@@ -117,7 +117,7 @@
 
 .. method:: AU_read.getnchannels()
 
-   Returns number of audio channels (1 for mone, 2 for stereo).
+   Returns number of audio channels (1 for mono, 2 for stereo).
 
 
 .. method:: AU_read.getsampwidth()