Make the "Replace the following file" option clearer to the users

[ane-gabriela]

While testing issue #34 I've noticed that the text "Replace the following file" can be a bit misleading for the user.

The text implies that the file will be replaced by a new one which includes content and also the Name/Title. In this case however, as stated in the comment #34 (comment), only the content is updated, the Naming remains of the first uploaded file.

I see 2 options in this case:

1. Rephrase the text, as to make the user understand that the Name/Title will not be changed
2. Add the option to also change the Name if the user wants it (have 2 options to preserve the current page name/title or change it to the new one)

[oanalavinia]

The message has been updated to make the option clearer