Comprehensive spelling/typo fixes.

Thanks to Josh Soref for generating these fixes.
diff --git a/contrib/wrt/README b/contrib/wrt/README
index 862046f..981db9f 100644
--- a/contrib/wrt/README
+++ b/contrib/wrt/README
@@ -4,7 +4,7 @@
 leases. Until a host renews (which may take hours/days) it will
 not exist in the DNS if dnsmasq's DDNS function is in use.
 
-*WRT systems remount all non-volatile fileystems read-only after boot,
+*WRT systems remount all non-volatile filesystems read-only after boot,
 so the normal leasefile will not work. They do, however have NV
 storage, accessed with the nvram command:
 
@@ -62,7 +62,7 @@
 use to half that. (The default limit in the distributed source is 150)
 
 Any UI script which reads the dnsmasq leasefile will have to be
-ammended, probably by changing it to read the output of 
+amended, probably by changing it to read the output of 
 `lease_update init` instead.