fix: incorrect descriptions of snapshot operations (#2513)

…unctions.

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# Rationale for this change
Currently, the documentation of these write functions contains some
inaccuracies regarding snapshot operations. These update methods do not
actually produce `replace` snapshots, but rather `overwrite` snapshots,
because the rewrite here modifies the data (dropping the records that
match the overwrite filter).

A `replace` snapshot is only generated when the table data itself is not
changed, such as during data file rewrites or manifest rewrites.

https://iceberg.apache.org/spec/#snapshots

<img width="1536" height="418" alt="image"
src="https://github.com/user-attachments/assets/a96b0e1c-86af-45da-98e5-58753e7f7482"
/>



## Are these changes tested?

## Are there any user-facing changes?

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Author: zhongyujiang

pyiceberg/table/__init__.py

@@ -569,7 +569,7 @@ def overwrite(
         An overwrite may produce zero or more snapshots based on the operation:
 
             - DELETE: In case existing Parquet files can be dropped completely.
-            - REPLACE: In case existing Parquet files need to be rewritten.
+            - OVERWRITE: In case existing Parquet files need to be rewritten to drop rows that match the overwrite filter.
             - APPEND: In case new data is being inserted into the table.
 
         Args:
@@ -629,7 +629,7 @@ def delete(
         A delete may produce zero or more snapshots based on the operation:
 
             - DELETE: In case existing Parquet files can be dropped completely.
-            - REPLACE: In case existing Parquet files need to be rewritten
+            - OVERWRITE: In case existing Parquet files need to be rewritten to drop rows that match the delete filter.
 
         Args:
             delete_filter: A boolean expression to delete rows from a table
@@ -1396,7 +1396,7 @@ def overwrite(
         An overwrite may produce zero or more snapshots based on the operation:
 
             - DELETE: In case existing Parquet files can be dropped completely.
-            - REPLACE: In case existing Parquet files need to be rewritten.
+            - OVERWRITE: In case existing Parquet files need to be rewritten to drop rows that match the overwrite filter..
             - APPEND: In case new data is being inserted into the table.
 
         Args: