bpo-37014: Update docstring and Documentation of fileinput.FileInput(). (GH-13545)

* bpo-37014: Update docstring and Documentation of fileinput.FileInput()

* Explain the behavior of fileinput.FileInput() when reading stdin.

* Update blurb.

* bpo-37014: Fix typo in the docstring and documentation.
diff --git a/Misc/ACKS b/Misc/ACKS
index 5c23df8..082fa56 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -55,6 +55,7 @@
 Chris Angelico
 Jérémy Anger
 Jon Anglin
+Michele Angrisano
 Ankur Ankan
 Heidi Annexstad
 Ramchandra Apte