change return to returns in line 124 (#3954)

in line 124, `return void` is wrong.
the correct syntax would be `returns`.

web/docs/guides/database/functions.mdx

@@ -121,7 +121,7 @@ $$; --6
 At it's most basic a function has the following parts:
 
 1. `create or replace function hello_world()`: The function declaration, where `hello_world` is the name of the function. You can use either `create` when creating a new function or `replace` when replacing an existing function. Or you can use `create or replace` together to handle either.
-2. `returns text`: The type of data that the function returns. If it returns nothing, you can `return void`. 
+2. `returns text`: The type of data that the function returns. If it returns nothing, you can `returns void`. 
 3. `language sql`: The language used inside the function body. This can also be a procedural language: `plpgsql`, `plv8`, `plpython`, etc.
 4. `as $$`: The function wrapper. Anything enclosed inside the `$$` symbols will be part of the function body.
 5. `select 'hello world';`: A simple function body. The final `select` statement inside a function body will be returned if there are no statements following it.