Add Alternatives. Mention "reverse proxy"

Author: dsmiley

README.md

@@ -1,7 +1,7 @@
 Smiley's HTTP Proxy Servlet
 ===========================
 
-This is an HTTP Proxy (aka gateway) in the form of a Java servlet.  An HTTP proxy is useful for AJAX applications to communicate with web accessible services on hosts other than where the web application is hosted.
+This is an HTTP Proxy (aka gateway) in the form of a Java servlet.  An HTTP proxy is useful for AJAX applications to communicate with web accessible services on hosts other than where the web application is hosted.  It's a _reverse proxy_, and not really a _forwarding proxy_ albeit the template form of the servlet may blur that line.
 
 This is hardly the first proxy, so why did I write it and thus why might you use it?
 
@@ -16,6 +16,8 @@ I've found such proxies to support a limited HTTP subset, such as only a GET req
 Disappointed at the situation, I set out to create a simple one that works well and that is well tested so I know it works.
 I suggest you use a well tested proxy instead of something non-tested that is perhaps better described as a proof-of-concept.
 
+If you need something more sophisticated than there are some alternatives listed at the bottom of this page.
+
 This proxy depends on [Apache HttpClient](http://hc.apache.org/httpcomponents-client-ga/), which offers another point of extension for this proxy.
 At some point I may write an alternative that uses the JDK and thus doesn't have any dependencies, which is desirable.
 In the mean time, you'll have to add the jar files for this and its dependencies:
@@ -199,3 +201,10 @@ Then create register Smiley's proxy servlet with Jetty through the Dropwizard se
             .addServlet("org.mitre.dsmiley.httpproxy.ProxyServlet", "foo/*")
             .setInitParameter("targetUri", configuration.getTargetUri());  
 ```
+
+Alternatives
+-------------
+This servlet is intentionally simple and limited in scope.  As such it may not meet your needs, so consider looking at these alternatives:
+* Jetty's ProxyServlet: https://www.eclipse.org/jetty/documentation/9.4.x/proxy-servlet.html  This is perhaps the closest competitor (simple, limited scope, no dependencies), and may very well already be on your classpath.
+* Netflix's Zuul: https://github.com/Netflix/zuul
+* Charon: https://github.com/mkopylec/charon-spring-boot-starter