Issue #9583: Document startup option/environment interaction.

Patch by Todd Rovito.
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 0d12126..cd4d02f 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -379,7 +379,10 @@
 Environment variables
 ---------------------
 
-These environment variables influence Python's behavior.
+These environment variables influence Python's behavior, they are processed
+before the command-line switches other than -E.  It is customary that
+command-line switches override environmental variables where there is a
+conflict.
 
 .. envvar:: PYTHONHOME
 
@@ -570,4 +573,3 @@
 
    If set, Python will print memory allocation statistics every time a new
    object arena is created, and on shutdown.
-
diff --git a/Misc/ACKS b/Misc/ACKS
index 7429f77..ba87ecb 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -901,6 +901,7 @@
 Saskia van Rossum
 Donald Wallace Rouse II
 Liam Routt
+Todd Rovito
 Craig Rowland
 Clinton Roy
 Paul Rubin