PEP 1: revert to PNG due to SVG rendering issues (#702)

pep-0001.txt

@@ -282,7 +282,8 @@ an API can replace version 1.
 
 The possible paths of the status of PEPs are as follows:
 
-.. image:: pep-0001-1.svg
+.. image:: pep-0001/process_flow.png
+   :alt: PEP process flow diagram
 
 While not shown in the diagram, "Accepted" PEPs may technically move to
 "Rejected" or "Withdrawn" even after acceptance. This will only occur if
@@ -381,7 +382,7 @@ Each PEP should have the following parts:
 
    This section may include key points and recommended documentation
    changes that would help users adopt a new feature or migrate their
-   code to use a language change. 
+   code to use a language change.
 
 
 PEP Formats and Templates