Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Remove build instruction from documentation

    Fuel/MCP no longer packages the installer in an iso, therefore
    these building instructions are obsolete.

    JIRA: FUEL-276

    Change-Id: Iee587be89078707cf0cf748212b94d69f1769e12
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index cd8a3e7..2e9fbb2 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit cd8a3e716911fdd784529078c14dfb859538dce2
+Subproject commit 2e9fbb20072005831fe96af94b8d1495f5eb30ab