Small clarity change for except*

In the except* discussion, four keywords are linked in a row: try, break, continue, and return. Visually, it is easy to miss the period after the "try". Adding a couple words (and the capitalization) after the period helps the reader notice the separate concerns of the keywords.

Author: gstein

Doc/reference/compound_stmts.rst

@@ -383,6 +383,7 @@ have ambiguous semantics.
 
 It is not possible to mix :keyword:`except` and :keyword:`!except*`
 in the same :keyword:`try`.
+The statements
 :keyword:`break`, :keyword:`continue` and :keyword:`return`
 cannot appear in an :keyword:`!except*` clause.