Update README

README.md

@@ -12,9 +12,16 @@
       ]
     }
 
-It's fast, doesn't mess with the data, and handles invalid JSON (within
-reason). For more information see the [project
-homepage][jp].
+It only adds and removes whitespace, which means that your data won’t get
+silently altered. For example, `"\u2603"` won’t get converted to `"☃"`, and
+`1.1e1` won’t turn into `11`. The ordering remains the same, and invalid JSON
+can be reformatted (within reason). This stuff shouldn’t matter, but people make
+mistakes even with a well defined format like JSON, and accurate tools are
+important when you’re trying to work out what’s gone wrong.
+
+For more information see the [project homepage][jp].
+
+[jp]: https://paulhammond.org/jp
 
 ## Installing
 
@@ -25,5 +32,22 @@ Using [Homebrew](http://brew.sh/):
 If you don't use Homebrew you can download a [precompiled binary][releases] and
 copy the `jp` file inside to somewhere in your path.
 
-[jp]: https://paulhammond.org/jp
 [releases]: https://github.com/paulhammond/jp/releases
+
+## Using
+
+To prettify a JSON file:
+
+    jp data.json
+
+To prettify from stdin, use - as the filename:
+
+    curl -sL https://phmmnd.me/names.json | jp -
+
+To compact a JSON file:
+
+    jp --compact data.json
+
+To get help:
+
+    jp --help