Update git submodules

* Update docs/submodules/barometer from branch 'master'
  - Merge "docs: update userguide with merged plugins"
  - docs: update userguide with merged plugins

    Update the userguide to reflect plugins that were merged to collectd master.

    Change-Id: I8947084d3038dda6fc10dcd91cb3f906dbd2e805
    Signed-off-by: Maryam Tahhan <maryam.tahhan@intel.com>

diff --git a/docs/submodules/barometer b/docs/submodules/barometer
index 4089293..dac61fc 160000 (submodule)
--- a/docs/submodules/barometer
+++ b/docs/submodules/barometer
@@ -1 +1 @@
-Subproject commit 4089293fce7a32e36181062a2ba562a371916865
+Subproject commit dac61fc5516b869971fb001769a3d30d5f55c987