DOC: Fix documentation for read_csv's mangle_dupe_cols (GH19203) (#19208)

Author: Bernhard10

doc/source/io.rst

@@ -149,7 +149,7 @@ squeeze : boolean, default ``False``
 prefix : str, default ``None``
   Prefix to add to column numbers when no header, e.g. 'X' for X0, X1, ...
 mangle_dupe_cols : boolean, default ``True``
-  Duplicate columns will be specified as 'X.0'...'X.N', rather than 'X'...'X'.
+  Duplicate columns will be specified as 'X', 'X.1'...'X.N', rather than 'X'...'X'.
   Passing in False will cause data to be overwritten if there are duplicate
   names in the columns.
 
@@ -548,7 +548,7 @@ these names so as to prevent data overwrite:
    pd.read_csv(StringIO(data))
 
 There is no more duplicate data because ``mangle_dupe_cols=True`` by default, which modifies
-a series of duplicate columns 'X'...'X' to become 'X.0'...'X.N'.  If ``mangle_dupe_cols
+a series of duplicate columns 'X'...'X' to become 'X', 'X.1',...'X.N'.  If ``mangle_dupe_cols
 =False``, duplicate data can arise:
 
 .. code-block :: python

pandas/io/parsers.py

@@ -114,7 +114,7 @@
 prefix : str, default None
     Prefix to add to column numbers when no header, e.g. 'X' for X0, X1, ...
 mangle_dupe_cols : boolean, default True
-    Duplicate columns will be specified as 'X.0'...'X.N', rather than
+    Duplicate columns will be specified as 'X', 'X.1', ...'X.N', rather than
     'X'...'X'. Passing in False will cause data to be overwritten if there
     are duplicate names in the columns.
 dtype : Type name or dict of column -> type, default None