[gnome-software/mwleeds/minor-docs-fixes: 1/2] README: Fix build instructions

[Phaedrus Leeds <mwleeds src gnome org>]

commit ad738d132c99775e093a0829f19de980e6cf5b25
Author: Phaedrus Leeds <mwleeds endlessos org>
Date:   Tue Feb 16 13:12:24 2021 -0800

    README: Fix build instructions
    
    Without this LD_LIBRARY_PATH addition, the executable fails to find
    libappstream.so. Also add some info about plugins.

 README.md | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index 2f76341cc..fe579e58e 100644
--- a/README.md
+++ b/README.md
@@ -33,12 +33,21 @@ For development discussion, join us on `#gnome-software` on [irc.gnome.org](http
 
 # Building
 
+Software uses a number of plugins and depending on your operating system you
+may want to disable or enable certain ones. For example on Fedora Silverblue
+you'd want to disable the packagekit plugin as it wouldn't work. See the list
+in `meson_options.txt` and use e.g. `-Dpackagekit=false` in the `meson` command
+below.
+
 Build locally with:
 ```
 $ meson --prefix $PWD/install build/
 $ ninja -C build/ all install
 $ killall gnome-software
-$ XDG_DATA_DIRS=install/share:$XDG_DATA_DIRS ./install/bin/gnome-software
+# On Fedora, RHEL, etc:
+$ XDG_DATA_DIRS=install/share:$XDG_DATA_DIRS LD_LIBRARY_PATH=install/lib64/:$LD_LIBRARY_PATH 
./install/bin/gnome-software
+# On Debian, Ubuntu, etc:
+$ XDG_DATA_DIRS=install/share:$XDG_DATA_DIRS LD_LIBRARY_PATH=install/lib/x86_64-linux-gnu/:$LD_LIBRARY_PATH 
./install/bin/gnome-software
 ```
 
 # Debugging