Update ReadMe with the potential issues and workarounds in ohpc_build

Some of the potential issues that may be encountered during OHPC provisioning with Ansible and vagrant had been covered here and quick work arounds are documented.

README.md

@@ -29,6 +29,11 @@ cluster with vagrant:
 vagrant up ohpc
 ```
 
+NOTE: After you run the above command if you were to get a `"kernel mismatch error"`. To get past this error please run:
+`vagrant ssh ohpc -c "uname -r"`.
+Copy and paste this kernel version in the group_vars/all to update the kernel version in the `build_kernel_ver` variable.
+
+
 The ansible config will bring the master node to the point where its
 ready to ingest compute nodes via wwnodescan and prompt to you
 start a compute node.  You can create a compute node and start it with
@@ -108,3 +113,12 @@ After this point you can connect to the web ui of the ood node, typically via
 http://localhost/8080
 
 The default user name and password for the web UI is 'vagrant'.
+
+## Issues and Work arounds
+
+If you encounter an issue with OHPC node provisioning due to GPG key errors as mentioned in https://github.com/jprorama/CRI_XCBC/issues/77. Please run the following command: 
+```
+vagrant box update
+```
+
+If you encounter an issue with nodes_vivify role in updating the slurm status on nodes, specifically the error `slurm_update error: Invalid node state specified`. Please increase the compute node memory. For example if you're using 4GB already increase the memory to 6GB in your Virtual Box.