add policy exemptions

Author: tfitzmac

articles/azure-resource-manager/management/resource-name-rules.md

@@ -104,6 +104,7 @@ In the following tables, the term alphanumeric refers to:
 > | locks | scope of assignment | 1-90 | Alphanumerics, periods, underscores, hyphens, and parenthesis.<br><br>Can't end in period. |
 > | policyAssignments | scope of assignment | 1-128 display name<br><br>1-64 resource name<br><br>1-24 resource name at management group scope | Display name can contain any characters.<br><br>Resource name can't use:<br>`<>*%&:\?.+/` or control characters. <br><br>Can't end with period or space. |
 > | policyDefinitions | scope of definition | 1-128 display name<br><br>1-64 resource name | Display name can contain any characters.<br><br>Resource name can't use:<br>`<>*%&:\?.+/` or control characters. <br><br>Can't end with period or space. |
+> | policyExemptions | scope of exemption | 1-128 display name<br><br>1-64 resource name | Display name can contain any characters.<br><br>Resource name can't use:<br>`<>*%&:\?.+/` or control characters. <br><br>Can't end with period or space. |
 > | policySetDefinitions | scope of definition | 1-128 display name<br><br>1-64 resource name | Display name can contain any characters.<br><br>Resource name can't use:<br>`<>*%&:\?.+/` or control characters. <br><br>Can't end with period or space. |
 > | roleAssignments | tenant | 36 | Must be a globally unique identifier (GUID). |
 > | roleDefinitions | tenant | 36 | Must be a globally unique identifier (GUID). |