[nautilus] README: Document runtime depedencies

[Carlos Soriano <csoriano src gnome org>]

commit 69244cd4285898b7fc16e7b13f32e3038df0dad2
Author: Carlos Soriano <csoriano1618 gmail com>
Date:   Thu Oct 4 07:58:00 2018 +0000

    README: Document runtime depedencies
    
    Closes https://gitlab.gnome.org/GNOME/nautilus/issues/395

 README.md | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/README.md b/README.md
index aa4fd534a..7d0097d44 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,10 @@ To build the development version of Nautilus and hack on the code
 see the [general guide](https://wiki.gnome.org/Newcomers/BuildProject)
 for building GNOME apps with Flatpak and GNOME Builder.
 
+# Runtime depepdencies
+- [Bubblewrap](https://github.com/projectatomic/bubblewrap) installed. Used for security reasons.
+- [Tracker](https://gitlab.gnome.org/GNOME/tracker) properly set up and with all features enabled. Used for 
fast search and metadata extraction, starred files and batch renaming.
+
 ## Mailing List
 
 The nautilus mailing list is nautilus-list gnome org. Read the [subscription