References to single-file version on Installation page

Hey Andy!  Hope I can help a bit. :)

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At the Installation page, two references to the single-file (previously referred to as "standalone") version of Ack 2.0 are currently leading to nowhere: 

1. The paragraph text has an anchor pointing to `ack-single-file`
2. The example `curl(1)` command refers to `ack-standalone`

The only choices in `static/` are actually:

* `ack-1.96-single-file`
* `ack-2.00-single-file`

Included commit points both references to `ack-2.00-single-file`.