README.md in stackprof-0.2.13 vs README.md in stackprof-0.2.14

@@ -4,11 +4,11 @@
 
 Inspired heavily by [gperftools](https://code.google.com/p/gperftools/), and written as a replacement for [perftools.rb](https://github.com/tmm1/perftools.rb).
 
 ## Requirements
 
-* Ruby 2.1+
+* Ruby 2.2+
 * Linux-based OS
 
 ## Getting Started
 
 ### Install
@@ -328,9 +328,10 @@
 `mode`      | mode of sampling: `:cpu`, `:wall`, `:object`, or `:custom` [c.f.](#sampling)
 `out`       | the target file, which will be overwritten
 `interval`  | mode-relative sample rate [c.f.](#sampling)
 `aggregate` | defaults: `true` - if `false` disables [aggregation](#aggregation)
 `raw`       | defaults `false` - if `true` collects the extra data required by the `--flamegraph` and `--stackcollapse` report types
+`metadata`  | defaults to `{}`. Must be a `Hash`. metadata associated with this profile
 `save_every`| (rack middleware only) write the target file after this many requests
 
 ## Todo
 
 * file/iseq blacklist