Update part0b.md

The "submit" button has "Save" label in the webapp - corrected.

Author: sergiiz

src/content/0/en/part0b.md

@@ -692,7 +692,7 @@ sequenceDiagram
     Note right of browser: The browser executes the callback function that renders the notes
 ```
 
-**Create a similar diagram** depicting the situation where the user creates a new note on the page <https://studies.cs.helsinki.fi/exampleapp/notes> by writing something into the text field and clicking the <i>submit</i> button.
+**Create a similar diagram** depicting the situation where the user creates a new note on the page <https://studies.cs.helsinki.fi/exampleapp/notes> by writing something into the text field and clicking the <i>Save</i> button.
 
 If necessary, show operations on the browser or on the server as comments on the diagram.