Try to improve grammar and use versionadded

Doc/lib/libunicodedata.tex

@@ -72,8 +72,9 @@ defines the following functions:
 \end{funcdesc}
 
 \begin{funcdesc}{east_asian_width}{unichr}
-  Returns the east asian width of assigned to the Unicode character
+  Returns the east asian width assigned to the Unicode character
   \var{unichr} as string.
+\versionadded{2.4}
 \end{funcdesc}
 
 \begin{funcdesc}{mirrored}{unichr}