Update OWNERS approvers and reviewers: cluster/vagrant

cluster/vagrant/OWNERS

@@ -1,2 +1,38 @@
-assignees:
-  - derekwaynecarr
+approvers:
+- derekwaynecarr
+reviewers:
+- thockin
+- lavalamp
+- smarterclayton
+- derekwaynecarr
+- caesarxuchao
+- vishh
+- mikedanese
+- liggitt
+- nikhiljindal
+- erictune
+- dchen1107
+- zmerlynn
+- justinsb
+- roberthbailey
+- eparis
+- jlowdermilk
+- piosz
+- jsafrane
+- jbeda
+- spxtr
+- madhusudancs
+- jayunit100
+- satnam6502
+- cjcullen
+- david-mcmahon
+- mfojtik
+- pweil-
+- dcbw
+- ivan4th
+- filbranden
+- dshulyak
+- k82cn
+- caseydavenport
+- johscheuer
+- rjnagal