ENH: Update docs to reference bionic

... instead of xenial

Author: davewalter

iaas-support/bosh-lite/README.md

@@ -69,7 +69,7 @@ STEMCELL_VERSION=$(bosh interpolate cf-deployment/cf-deployment.yml --path /stem
 
 bosh \
   upload-stemcell \
-  https://bosh.io/d/stemcells/bosh-warden-boshlite-ubuntu-xenial-go_agent?v=${STEMCELL_VERSION}
+  https://bosh.io/d/stemcells/bosh-warden-boshlite-ubuntu-bionic-go_agent?v=${STEMCELL_VERSION}
 ```
 
 

texts/deployment-guide.md

@@ -161,7 +161,7 @@ export STEMCELL_VERSION=$(bosh interpolate cf-deployment.yml --path=/stemcells/a
 ```
 Now you can upload the stemcell:
 ```
-bosh upload-stemcell https://bosh.io/d/stemcells/bosh-${IAAS_INFO}-ubuntu-xenial-go_agent?v=${STEMCELL_VERSION}
+bosh upload-stemcell https://bosh.io/d/stemcells/bosh-${IAAS_INFO}-ubuntu-bionic-go_agent?v=${STEMCELL_VERSION}
 ```
 
 ### Step 8: Deploy CF

units/README.md

@@ -72,8 +72,8 @@ For example, given the following manifest snippet:
 ```
 stemcells:
 - alias: default
-  os: ubuntu-xenial
-  version: "456.16"
+  os: ubuntu-bionic
+  version: "1.1"
 ```
 
 and the following ops-file: