[tracker/sam/readme-updates] README: Add note about missing dependency errors

[Sam Thursfield <sthursfield src gnome org>]

commit 1194a2ffd01c56cb46c54f8ca64b71e4d34ee297
Author: Sam Thursfield <sam afuera me uk>
Date:   Thu May 23 22:22:23 2019 +0200

    README: Add note about missing dependency errors

 README.md | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/README.md b/README.md
index 88737587d..ca7dd4e5a 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,12 @@ You can do this by cloning both repos, then creating a symlink in the
 Now you can run the commands below to build Tracker and install it in a
 new, isolated prefix named `opt/tracker` inside your home folder.
 
+> NOTE: If you see 'dependency not found' errors from Meson, that means there
+> is a package missing on your computer that you need to install so you can
+> compile Tracker. On Ubuntu/Debian, you can run `apt build-dep tracker-miners`
+> and on Fedora `dnf build-dep tracker-miners` to install all the necessary
+> packages.
+
     cd tracker-miners
     meson ./build --prefix=$HOME/opt/tracker -Dtracker_core=subproject
     cd build