Allow setting oom_score_adj for services spawned from init

(cherry picked from commit f7adf8e4739812a2a4f194b17f84f4b9df42d04b)

Bug: 29831602
Change-Id: I4d24264bb6e879935a0b2adbb2e49ddf458980cf
diff --git a/init/readme.txt b/init/readme.txt
index 56918f6..bc3874a 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -191,6 +191,10 @@
 namespace <pid|mnt>
   Enter a new PID or mount namespace when forking the service.
 
+oom_score_adjust <value>
+   Sets the child's /proc/self/oom_score_adj to the specified value,
+   which must range from -1000 to 1000.
+
 
 Triggers
 --------