Rewriting novice shell lesson so that everything refers to Nelle instead of Vlad.

[gvwilson]

Inspired by #437.

[DevasenaInupakutika]

I'll work on this. So, as to confirm, do we need to change the examples and references to Nelle based on data in Nelle's directory but concepts and topics would be same?

[gvwilson]

Thanks Devasena - what this needs now is a careful proof-read to make sure that everything is consistent (i.e., that we're always referring to Nelle, that we're talking about /users/nelle, that the pronoun is 'she' rather than 'he', etc.).

[ChristinaLK]

I didn't see any inconsistencies - looks good!

[gvwilson]

Thanks!