fix: correct/clarify to_property_graph method

Author: jaidisido

awswrangler/neptune/_neptune.py

@@ -127,17 +127,19 @@ def to_property_graph(
     """Write records stored in a DataFrame into Amazon Neptune.
 
     If writing to a property graph then DataFrames for vertices and edges must be written separately.
+
     DataFrames for vertices must have a ~label column with the label and a ~id column for the vertex id.
-    If the ~id column does not exist, the specified id does not exists, or is empty then a new vertex will be added.
-    If no ~label column exists an exception will be thrown.
+    If the ~id column does not exist, the specified id does not exist, or is empty then a new vertex will be added.
+
     DataFrames for edges must have a ~id, ~label, ~to, and ~from column.  If the ~id column does not exist
-    the specified id does not exists, or is empty then a new edge will be added. If no ~label, ~to, or ~from column
-    exists an exception will be thrown.
+    the specified id does not exist, or is empty then a new edge will be added.
+
+    Existing ~id values will be overwritten. If no ~id, ~label, ~to, or ~from column exists,
+    an InvalidArgumentValue exception will be thrown.
 
     If you would like to save data using `single` cardinality then you can postfix (single) to the column header and
     set use_header_cardinality=True (default).  e.g. A column named `name(single)` will save the `name` property
-    as single
-    cardinality.  You can disable this by setting by setting `use_header_cardinality=False`.
+    as single cardinality. You can disable this by setting by setting `use_header_cardinality=False`.
 
     Parameters
     ----------