Small edit to a docstring

app.py

@@ -152,7 +152,7 @@ def scatter_relation(x: str, y: str, size: str, data_frame: pd.DataFrame = None)
 
 
 def create_variable_analysis():
-    """Function returns a page with gapminder data to do variable analysis."""
+    """Function that returns a page with gapminder data to do variable analysis."""
     page_variable = vm.Page(
         title="Variable Analysis",
         description="Analyzing population, GDP per capita and life expectancy on country and continent level",