[mod] modified readme to include query string support

- considered experimental until more test coverage is done

README.md

@@ -44,6 +44,11 @@ JSON_REQUEST_BODY='{
   "public_ip": false
 }'
 http post $API_SERVER/admin/client $API_KEY <<< $JSON_REQUEST_BODY
+
+# Alternatively using query strings (be sure to encode special characters in the param values)
+API_KEY='X-API-Key=MdSUxrQQ.d5d40cd9.e2s1BsQEqmSE5MqyHYbDBVxGr/KY4BYIV5QkdjiCOF0='
+CLIENT_PARAMS='name=clientA&description=Client+across+the+river&permission=rw&public_ip=false'
+http post "$API_SERVER/admin/client?$API_KEY&$CLIENT_PARAMS"
 ```
 Updating a write client's `ipv4`:
 ```bash
@@ -80,6 +85,8 @@ A detailed and interactive specification can be found in the [demo](https://demo
 
 All requests except for `/public/*` require a valid `X-API-Key` header with appropriate permission.
 
+**Experimental:** All parameters (including `X-API-Key`) can be passed as query string.
+
 The following is a quick overview of the available commands.
 
 ### Admin
@@ -131,5 +138,7 @@ RAILS_DEMO_RESET: 60m
 ## Roadmap
 
 * `Public Mode` - to allow for quick deployment without having to create clients/api-keys in a trusted environment (see #1)
-* Support Query Strings - as alternative to api key in header and json body
+* ~~Support Query Strings - as alternative to api key in header and json body~~ (merged 297016e799)
+  * add full test coverage for query strings (considered experimental until then)
+  * add query strings to `api.yml` and additional examples
 * DNS Server in Docker container - resolve `client_name`s via DNS server