[BUG] superfluous double quote (`"`) in MAKE_A_NEW_BACK_END.md

[albert-github]

In the file MAKE_A_NEW_BACK_END.md of the master version we see at line 35:

- `_dash-layout"`: Gives the JSON structure of the initial Dash components to render on the page (`app.layout` in Python)

I think the " should not be present and the line should read:

- `_dash-layout`: Gives the JSON structure of the initial Dash components to render on the page (`app.layout` in Python)