Update cpu_allocation.md

Jira Ticket : https://rackspace.atlassian.net/browse/OSPC-68
Description: What is our virtual server over-commit ratio.

This branch include update to default cpu_allocation_ratio to 8 from 1   and we have tried to provide a  guideline to calculate this value for your hardware configuration used for openstack deployment.

docs/cpu_allocation.md

@@ -1,11 +1,10 @@
-
-#CPU allocation Guide
+# CPU allocation Guide
 
 By default openstack helm provide cpu allocation of 3:1. For a production deployment, cpu allocation ratio need to be decided based on multiple factors like  hardware configuration of compute node (number of CPU core available ), required  performance of workload, goal of efficient usage of available resource etc. 
 We are using  HPE DL380 Gen9 Servers with 2 CPU socket and 18 cores per CPU socket and 2 threads per core to get cpu allocation for our deployment. We are considering below two cases here
 
 
-Case 1 : CPU allocation ratio for shared CPU  
+## Case 1 : CPU allocation ratio for shared CPU  
 
 Type of workload :  Whether workload is CPU intensive or not? if yes, then you need  to decide number of cpu cores for such workload. Create flavor according to workload cpu requirement.
 
@@ -33,7 +32,7 @@ So here we get approx CPU allocation ratio of 11:1.
 
 
 
-Case 2: Shared workload with CPU pining: 
+## Case 2: Shared workload with CPU pining: 
 
 There may be requirement to run CPU pinned VM along with floating instances (shared cpus). In such case CPU allocation for  compute node will be different from rest of nodes. Lets see how to get cpu allocation for such type of compute nodes: