Update Jackson links from nonexistent 2.1.1 javadocs to 2.10

The current links are broken, maybe 2.1.1 never existed or was taken
offline (2.1 does exist, oddly).  And the current Leiningen dependency
is set to 2.10 so this matches better anyway.

README.md

@@ -311,9 +311,9 @@ It's experimental, like the name says. Based on [Tigris](http://github.com/dakro
 
 ## Advanced customization for factories
 See
-[this](http://fasterxml.github.com/jackson-core/javadoc/2.1.1/com/fasterxml/jackson/core/JsonFactory.Feature.html)
+[this](http://fasterxml.github.com/jackson-core/javadoc/2.10/com/fasterxml/jackson/core/JsonFactory.Feature.html)
 and
-[this](http://fasterxml.github.com/jackson-core/javadoc/2.1.1/com/fasterxml/jackson/core/JsonParser.Feature.html)
+[this](http://fasterxml.github.com/jackson-core/javadoc/2.10/com/fasterxml/jackson/core/JsonParser.Feature.html)
 for a list of features that can be customized if desired. A custom
 factory can be used like so: