fix some typos and one grammar

looks like same typo was repeated to different files

doc/examples/kea4/several-subnets.json

@@ -19,7 +19,7 @@
 
 # Addresses will be assigned with the valid lifetimes being 4000.
 # Client is told to start renewing after 1000 seconds. If the server
-# does not repond after 2000 seconds since the lease was granted, client
+# does not respond after 2000 seconds since the lease was granted, client
 # is supposed to start REBIND procedure (emergency renewal that allows
 # switching to a different server).
   "valid-lifetime": 4000,

doc/examples/kea6/advanced.json

@@ -51,7 +51,7 @@
 
 # Addresses will be assigned with preferred and valid lifetimes
 # being 3000 and 4000, respectively. Client is told to start
-# renewing after 1000 seconds. If the server does not repond
+# renewing after 1000 seconds. If the server does not respond
 # after 2000 seconds since the lease was granted, client is supposed
 # to start REBIND procedure (emergency renewal that allows switching
 # to a different server).

doc/examples/kea6/multiple-options.json

@@ -18,7 +18,7 @@
 
 # Addresses will be assigned with preferred and valid lifetimes
 # being 3000 and 4000, respectively. Client is told to start
-# renewing after 1000 seconds. If the server does not repond
+# renewing after 1000 seconds. If the server does not respond
 # after 2000 seconds since the lease was granted, client is supposed
 # to start REBIND procedure (emergency renewal that allows switching
 # to a different server).

doc/examples/kea6/several-subnets.json

@@ -19,7 +19,7 @@
 
 # Addresses will be assigned with preferred and valid lifetimes
 # being 3000 and 4000, respectively. Client is told to start
-# renewing after 1000 seconds. If the server does not repond
+# renewing after 1000 seconds. If the server does not respond
 # after 2000 seconds since the lease was granted, client is supposed
 # to start REBIND procedure (emergency renewal that allows switching
 # to a different server).

doc/examples/kea6/simple.json

@@ -20,7 +20,7 @@
 
 # Addresses will be assigned with preferred and valid lifetimes
 # being 3000 and 4000, respectively. Client is told to start
-# renewing after 1000 seconds. If the server does not repond
+# renewing after 1000 seconds. If the server does not respond
 # after 2000 seconds since the lease was granted, client is supposed
 # to start REBIND procedure (emergency renewal that allows switching
 # to a different server).

src/bin/keactrl/kea.conf.pre

 # This is a basic configuration for the Kea DHCPv4 and DHCPv6 servers.
 # Subnet declarations are commented out and no interfaces are listed.
-# Therefore, the servers will not listen to or respond any queries.
+# Therefore, the servers will not listen or respond to any queries.
 # The basic configuration must be extended to specify interfaces on
 # which the servers should listen. Also, subnets and options must be
 # declared.
@@ -48,7 +48,7 @@
 
 # Addresses will be assigned with preferred and valid lifetimes
 # being 3000 and 4000, respectively. Client is told to start
-# renewing after 1000 seconds. If the server does not repond
+# renewing after 1000 seconds. If the server does not respond
 # after 2000 seconds since the lease was granted, client is supposed
 # to start REBIND procedure (emergency renewal that allows switching
 # to a different server).