Split the code example (neo4j#2226)

Based on the PR neo4j#2223

Author: NataliaIvakina

modules/ROOT/pages/installation/linux/rpm.adoc

@@ -24,6 +24,12 @@ Use the following as `root` to add the repository:
 [source, shell, subs="attributes"]
 ----
 rpm --import https://debian.neo4j.com/neotechnology.gpg.key
+----
++
+Create a `neo4j.repo` file by running the following:
++
+[source, shell, subs="attributes"]
+----
 cat << EOF >  /etc/yum.repos.d/neo4j.repo
 [neo4j]
 name=Neo4j RPM Repository