Update dns-limits.md

We updated our default limits and added a new limit

Author: jonbeck7

includes/dns-limits.md

@@ -14,7 +14,8 @@ ms.author: greglin
 | Public DNS zones per subscription |250 <sup>1</sup> |
 | Record sets per public DNS zone |10,000 <sup>1</sup> |
 | Records per record set in public DNS zone |20 <sup>1</sup> |
-| Number of Alias records for a single Azure resource |20|
+| TXT Records per record set in public DNS zone |400 |
+| Number of Alias records for a single Azure resource |50|
 
 <sup>1</sup>If you need to increase these quota limits, contact Azure Support.