Update 04-merge-conflicts.md

I was following this guide on how to resolve the merge conflicts I was having in a patch I created, but I was not able to achieve that following them. I was obtaining the following error when I was reaching step 4 (rebase with Master):

<file>: needs merge                                                             
error: cannot rebase: You have unstaged changes.                                               
error: additionally, your index contains uncommitted changes.                                                                                                                                 
error: Please commit or stash them.   

And when I did the necessary fixes, I was not able to rebase and commit the changes for the patch in question.

I ended up using the steps I post in this change, and everything worked properly.

requested review from @aticig

assigned to @escaleira

requested review from @beierlm

Hello Pedro, Your patch looks good.

approved this merge request

I added @beierlm for additional review and complete merge process.