Add support for Query String filtering

docs/basics.md

@@ -109,6 +109,7 @@ Following is the list of existing matcher rules along with examples:
 - `PathPrefix: /products/, /articles/{category}/{id:[0-9]+}`: Match request prefix path. It accepts a sequence of literal and regular expression prefix paths.
 - `PathPrefixStrip: /products/`: Match request prefix path and strip off the path prefix prior to forwarding the request to the backend. It accepts a sequence of literal prefix paths. Starting with Traefik 1.3, the stripped prefix path will be available in the `X-Forwarded-Prefix` header.
 - `PathPrefixStripRegex: /articles/{category}/{id:[0-9]+}`: Match request prefix path and strip off the path prefix prior to forwarding the request to the backend. It accepts a sequence of literal and regular expression prefix paths. Starting with Traefik 1.3, the stripped prefix path will be available in the `X-Forwarded-Prefix` header.
+- `Query: foo=bar, bar=baz`: Match Query String parameters. It accepts a sequence of key=value pairs.
 
 In order to use regular expressions with Host and Path matchers, you must declare an arbitrarily named variable followed by the colon-separated regular expression, all enclosed in curly braces. Any pattern supported by [Go's regexp package](https://golang.org/pkg/regexp/) may be used. Example: `/posts/{id:[0-9]+}`.