update README

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
remove obsolete loggregator.servers property

[#75821502]
bump loggregator

d6f1eca remove unused dropsonde submodule reference
8d89944 remove unused loggregator.servers snippet
fca3026 fix go-etcd submodule bump
da225a9 bump etcd
18aa71d Fixing the docs images to refelct the new infrastructure
a505e71 go fmt
a6c524e Whitespace change.
b7052db bump loggregatorlib