Docs : Clarified File open vs. Import for issue #13684

[Renuka-Kamani]

Fulfills the documentation task requested in issue #13684 by clarifying the difference between File -> Open and File -> Import for new users.

[ThiloteE]

Hello, Rekuna-Makani :-) Thanks for looking into this. Here is a little feedback:

1. I cannot find issue #13684. Could you please provide a link?
2. I think your clarifications in the documentation should also be placed at https://docs.jabref.org/collect/ in two more detailed sections. Since Opening a library will not contain a lot of text, maybe Open and Import even should be merged together into one section, but I cannot think of a good filename and combined header for that section. In any case, then you could link to this detailed description and only add a short sentence in the Getting Started part, such as "You can also [open](link to user-documentation/en/collect/Open) an existing library or [import](link to user-documentation/en/collect/import) entries from an existing library into your new library." (Use Markdown syntax). In any case, where you are trying to place it is a little hidden and I think Opening and Importing a library could be a little bit more prominent in the documentation. I know you and me, we will not have problems, but I have met people that lack intuition, when it comes to computers and first have to learn the basics.

[ThiloteE]

Suggested change

	* *File -> Open* is used to open a new library file (or an existing one). JabRef can keep multiple libraries open at the same time.
	* *File -> Open* is used to open an already existing BibTeX library file (*.bib). JabRef can keep multiple libraries open at the same time.

[ThiloteE]

Suggested change

	* *File -> Import* is used to add the contents (all the entries) of an existing BibTeX or other reference file into the *library you currently have open*.
	* *File -> Import* is used to add the contents (all the entries) of an existing BibTeX or other reference file into the *library you currently have open*. Import Filters will be applied.