fconf: Add documentation

Change-Id: I606f9491fb6deebc6845c5b9d7db88fc5c895bd9
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
diff --git a/docs/glossary.rst b/docs/glossary.rst
index 2f19df5..3da30b0 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -42,12 +42,18 @@
    DT
       Device Tree
 
+   DTB
+      Device Tree Blob
+
    EL
       Exception Level
 
    EHF
       Exception Handling Framework
 
+   FCONF
+      Firmware Configuration Framework
+
    FDT
       Flattened Device Tree