Add a doc string for the edit cell method, which was missing.

Author: Tim Shawver

qgrid/grid.py

@@ -1689,6 +1689,20 @@ def _add_row(self, row):
         return index_col_val
 
     def edit_cell(self, index, column, value):
+        """
+        Edit a cell of the grid, given the index and column of the cell
+        to edit, as well as the new value of the cell. Results in a
+        ``cell_edited`` event being fired.
+
+        Parameters
+        ----------
+        index : object
+            The index of the row containing the cell that is to be edited.
+        column : str
+            The name of the column containing the cell that is to be edited.
+        value : object
+            The new value for the cell.
+        """
         old_value = self._df.loc[index, column]
         self._df.loc[index, column] = value
         self._unfiltered_df.loc[index, column] = value