Fix some typos in documents (#2592)

Signed-off-by: Xiao An <hac@zju.edu.cn>

README.md

@@ -16,7 +16,7 @@ CoreDNS is a fast and flexible DNS server. The keyword here is *flexible*: with
 are able to do what you want with your DNS data by utilizing plugins. If some functionality is not
 provided out of the box you can add it by [writing a plugin](https://coredns.io/explugins).
 
-CoreDNS can listen for DNS request coming in over UDP/TCP (go'old DNS), TLS ([RFC
+CoreDNS can listen for DNS requests coming in over UDP/TCP (go'old DNS), TLS ([RFC
 7858](https://tools.ietf.org/html/rfc7858)) and [gRPC](https://grpc.io) (not a standard).
 
 Currently CoreDNS is able to:
@@ -86,7 +86,7 @@ When starting CoreDNS without any configuration, it loads the
 CoreDNS-001
 ~~~
 
-Any query send to port 53 should return some information; your sending address, port and protocol
+Any query sent to port 53 should return some information; your sending address, port and protocol
 used.
 
 If you have a Corefile without a port number specified it will, by default, use port 53, but you
@@ -94,7 +94,7 @@ can override the port with the `-dns.port` flag:
 
 `./coredns -dns.port 1053`, runs the server on port 1053.
 
-Start a simple proxy, you'll need to be root to start listening on port 53.
+Start a simple proxy. You'll need to be root to start listening on port 53.
 
 `Corefile` contains:
 

plugin/etcd/README.md

@@ -113,7 +113,7 @@ etcd skydns.local {
 
 Before getting started with these examples, please setup `etcdctl` (with `etcdv3` API) as explained [here](https://coreos.com/etcd/docs/latest/dev-guide/interacting_v3.html). This will help you to put sample keys in your etcd server.
 
-If you prefer, you can use `curl` to populate the `etcd` server, but with `curl` the endpoint URL depends on the version of `etcd`. For instance, `etcd v3.2` or before uses only [CLIENT-URL]/v3alpha/* while `etcd v3.5` or later uses [CLIENT-URL]/v3/* . Also, Key and Value must be base64 encoded in the JSON payload. With, `etcdctl` these details are automatically taken care off. You can check [this document](https://github.com/coreos/etcd/blob/master/Documentation/dev-guide/api_grpc_gateway.md#notes) for details.
+If you prefer, you can use `curl` to populate the `etcd` server, but with `curl` the endpoint URL depends on the version of `etcd`. For instance, `etcd v3.2` or before uses only [CLIENT-URL]/v3alpha/* while `etcd v3.5` or later uses [CLIENT-URL]/v3/* . Also, Key and Value must be base64 encoded in the JSON payload. With `etcdctl` these details are automatically taken care off. You can check [this document](https://github.com/coreos/etcd/blob/master/Documentation/dev-guide/api_grpc_gateway.md#notes) for details.
 
 ### Reverse zones
 
@@ -142,7 +142,7 @@ reverse.skydns.local.
 
 ### Zone name as A record
 
-The zone name itself can be used A record. This behavior can be achieved by writing special entries to the ETCD path of your zone. If your zone is named `skydns.local` for example, you can create an `A` record for this zone as follows:
+The zone name itself can be used as A record. This behavior can be achieved by writing special entries to the ETCD path of your zone. If your zone is named `skydns.local` for example, you can create an `A` record for this zone as follows:
 
 ~~~
 % etcdctl put /skydns/local/skydns/ '{"host":"1.1.1.1","ttl":60}'

plugin/route53/README.md

@@ -37,7 +37,7 @@ route53 [ZONE:HOSTED_ZONE_ID...] {
 *   `upstream`is used for resolving services that point to external hosts (eg. used to resolve
     CNAMEs). CoreDNS will resolve against itself.
 
-*   `credentials` used for reading the credential file and setting the profile name for a given
+*   `credentials` is used for reading the credential file and setting the profile name for a given
     zone.
 
 *   **PROFILE** AWS account profile name. Defaults to `default`.