add installation and update Readme

manifests/main/install.pp

@@ -6,4 +6,14 @@
 class prometheus_cd::main::install (
 ) inherits prometheus_cd::params {
   require prometheus_cd::main::yumrepo
+  if $manage_prometheus  == true {
+    package { $reqpackage_prom:
+      ensure => $pkg_ensure,
+    }
+  }
+  if $manage_node_exporter == true {
+    package { $reqpackage_ne:
+      ensure => $pkg_ensure,
+    }
+  }
 }