Replace phosphor-rest-server reference

phosphor-rest-server is no longer a default repo.
phosphor-state-manager makes more sense here.

Change-Id: I00540f7d27731b8be5386d8ac8e7efb8099a3546
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c370a2d..689cc27 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -214,7 +214,8 @@
 
 From your OpenBMC git repository, add a remote to the Gerrit server, where
 'openbmc_repo' is the current git repository you're working on, such as
-phosphor-rest-server, and 'openbmc.gerrit' is the name of the Host previously added:
+phosphor-state-manager, and 'openbmc.gerrit' is the name of the Host previously
+added:
 
   `git remote add gerrit ssh://openbmc.gerrit/openbmc/openbmc_repo`