fixing variable name missmatch (identityName)

fixing identityName variable name mismatch. There was a typo - idenity instead of identity. Although further in the script a correct name "identity" was referenced.
Also fixing issue with the custom role name in the role assigment create. As the role name contains spaces, it must be enclosed in quotes.

Author: astaykov

articles/virtual-machines/linux/image-builder-gallery.md

@@ -85,14 +85,14 @@ Image Builder will use the [user-identity](../../active-directory/managed-identi
 
 ```bash
 # create user assigned identity for image builder to access the storage account where the script is located
-idenityName=aibBuiUserId$(date +'%s')
-az identity create -g $sigResourceGroup -n $idenityName
+identityName=aibBuiUserId$(date +'%s')
+az identity create -g $sigResourceGroup -n $identityName
 
 # get identity id
 imgBuilderCliId=$(az identity show -g $sigResourceGroup -n $identityName --query clientId -o tsv)
 
 # get the user identity URI, needed for the template
-imgBuilderId=/subscriptions/$subscriptionID/resourcegroups/$sigResourceGroup/providers/Microsoft.ManagedIdentity/userAssignedIdentities/$idenityName
+imgBuilderId=/subscriptions/$subscriptionID/resourcegroups/$sigResourceGroup/providers/Microsoft.ManagedIdentity/userAssignedIdentities/$identityName
 
 # this command will download an Azure role definition template, and update the template with the parameters specified earlier.
 curl https://raw.githubusercontent.com/azure/azvmimagebuilder/master/solutions/12_Creating_AIB_Security_Roles/aibRoleImageCreation.json -o aibRoleImageCreation.json
@@ -110,7 +110,7 @@ az role definition create --role-definition ./aibRoleImageCreation.json
 # grant role definition to the user assigned identity
 az role assignment create \
     --assignee $imgBuilderCliId \
-    --role $imageRoleDefName \
+    --role "$imageRoleDefName" \
     --scope /subscriptions/$subscriptionID/resourceGroups/$sigResourceGroup
 ```