Fix typos in architecture.md & xml.md (#364)

docs/en-us/user/configuration/xml.md

@@ -63,7 +63,7 @@ tag  | purpose | introduction
 Take timeout as an example, here is the priorities, from high to low (retries, loadbalance, actives also applies  the same rule): 
 
 * method level，interface level，default/global level。
-* at the same leveel, consumer has higher priority than provider
+* at the same level, consumer has higher priority than provider
 
 Configurations on the provider side are passed to the consumer side through registry in the form of URL.
 

docs/en-us/user/preface/architecture.md

@@ -37,7 +37,7 @@ Dubbo has the following features: Connectivity, Robustness, Scalability and Upgr
 ## Robustness
 
 * `Monitor`'s downtime doesn't affect the usage, only lose some sampling data
-* When the DB server goes down, `Register` can return service `Provider`s list to `Consumer` by checking its cache, but new `Provider` cannot regiter any services
+* When the DB server goes down, `Register` can return service `Provider`s list to `Consumer` by checking its cache, but new `Provider` cannot register any services
 * `Register` is a peer cluster, it will automatically switch to another when any instance goes down
 * Even all `Register`'s instances go down, `Provider` and `Consumer` can still conmunicate by checking their local cache
 * Service `Provider`s are stateless, one instance's downtime doesn't affect the usage