typo fix

Signed-off-by: Bearice Ren <bearice@gmail.com>

libnetwork/docs/ipam.md

@@ -226,7 +226,7 @@ Where:
 
 This API is for releasing an IP address.
 
-For this API, the remote driver will receive a POST message to the URL `/IpamDriver.RleaseAddress` with the following payload:
+For this API, the remote driver will receive a POST message to the URL `/IpamDriver.ReleaseAddress` with the following payload:
 
     {
 		"PoolID": string
@@ -266,4 +266,4 @@ If true, on `CreateEndpoint()` request, libnetwork will generate a random MAC ad
 
 ## Appendix
 
-A Go extension for the IPAM remote API is available at [docker/go-plugins-helpers/ipam](https://github.com/docker/go-plugins-helpers/tree/master/ipam)
+A Go extension for the IPAM remote API is available at [docker/go-plugins-helpers/ipam](https://github.com/docker/go-plugins-helpers/tree/master/ipam)