Add discussion of LIBS_FROM_GIT

Add a pointer to installing clients via LIBS_FROM_GIT to local.conf
sample.  Mention in the git tree setup that the projects within are
usually installed via released pip versions.

Change-Id: I245094e51ea4a8ce983f6a1e48b6ab7ca5d309d0

samples/local.conf

@@ -63,7 +63,8 @@ LOGDAYS=2
 # Using milestone-proposed branches
 # ---------------------------------
 
-# Uncomment these to grab the milestone-proposed branches from the repos:
+# Uncomment these to grab the milestone-proposed branches from the
+# repos:
 #CINDER_BRANCH=milestone-proposed
 #GLANCE_BRANCH=milestone-proposed
 #HORIZON_BRANCH=milestone-proposed
@@ -74,6 +75,13 @@ LOGDAYS=2
 #NEUTRON_BRANCH=milestone-proposed
 #SWIFT_BRANCH=milestone-proposed
 
+# Using git versions of clients
+# -----------------------------
+# By default clients are installed from pip.  See LIBS_FROM_GIT in
+# stackrc for details on getting clients from specific branches or
+# revisions.  e.g.
+# LIBS_FROM_GIT="python-ironicclient"
+# IRONICCLIENT_BRANCH=refs/changes/44/2.../1
 
 # Swift
 # -----

stackrc

@@ -268,6 +268,7 @@ GITBRANCH["tempest-lib"]=${TEMPEST_LIB_BRANCH:-master}
 ##############
 #
 #  OpenStack Client Library Components
+#   Note default install is from pip, see LIBS_FROM_GIT
 #
 ##############
 
@@ -317,6 +318,7 @@ GITDIR["python-openstackclient"]=$DEST/python-openstackclient
 ###################
 #
 #  Oslo Libraries
+#   Note default install is from pip, see LIBS_FROM_GIT
 #
 ###################