Improve readability of `formataddr` docstring (GH-20963)



For me as a non native English speaker, the sentence with its embedded clause was very hard to understand.

modified:   Lib/email/utils.py

Automerge-Triggered-By: @csabella
diff --git a/Lib/email/utils.py b/Lib/email/utils.py
index b137ce3..1a7719d 100644
--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -81,7 +81,7 @@
     If the first element of pair is false, then the second element is
     returned unmodified.
 
-    Optional charset if given is the character set that is used to encode
+    The optional charset is the character set that is used to encode
     realname in case realname is not ASCII safe.  Can be an instance of str or
     a Charset-like object which has a header_encode method.  Default is
     'utf-8'.