docs: Add that the number_of_rows will be set to 0 when removing th…

…e last column (#384)

Closes #276 

### Summary of Changes

When removing the only column in a 1-column-table, the number_of_rows
property is set to 0. This behaviour should be documented in the Table
class docstring as well as in the following methods:
Table.keep_only_columns, Table.remove_columns,
Table.remove_columns_with_missing_values and
Table.remove_columns_with_non_numerical_values.

<!-- Please provide a summary of changes in this pull request, ensuring
all changes are explained. -->

---------

Co-authored-by: patrikguempel <[email protected]>

src/safeds/data/tabular/containers/_table.py

@@ -54,6 +54,8 @@ class Table:
     | [from_columns][safeds.data.tabular.containers._table.Table.from_columns]     | Create a table from a list of columns. |
     | [from_rows][safeds.data.tabular.containers._table.Table.from_rows]           | Create a table from a list of rows.    |
 
+    Note: When removing the last column of the table, the `number_of_columns` property will be set to 0.
+
     Parameters
     ----------
     data : Mapping[str, Sequence[Any]] | None
@@ -825,6 +827,8 @@ def keep_only_columns(self, column_names: list[str]) -> Table:
 
         This table is not modified.
 
+        Note: When removing the last column of the table, the `number_of_columns` property will be set to 0.
+
         Parameters
         ----------
         column_names : list[str]
@@ -857,6 +861,8 @@ def remove_columns(self, column_names: list[str]) -> Table:
 
         This table is not modified.
 
+        Note: When removing the last column of the table, the `number_of_columns` property will be set to 0.
+
         Parameters
         ----------
         column_names : list[str]
@@ -889,6 +895,8 @@ def remove_columns_with_missing_values(self) -> Table:
 
         This table is not modified.
 
+        Note: When removing the last column of the table, the `number_of_columns` property will be set to 0.
+
         Returns
         -------
         table : Table
@@ -902,6 +910,8 @@ def remove_columns_with_non_numerical_values(self) -> Table:
 
         This table is not modified.
 
+        Note: When removing the last column of the table, the `number_of_columns` property will be set to 0.
+
         Returns
         -------
         table : Table