Flesh out README.

README.md

@@ -1,2 +1,21 @@
-# passbleed
-Check your keepass URLs against cloudbleed
+# Passbleed
+Passbleed checks your exported KeePass database against the ClodBleed list
+found [here](https://github.com/pirate/sites-using-cloudflare).
+
+## Download
+Head to the [Releases](https://github.com/jinks/passbleed/releases) page and grab a copy for your OS (only the Linux release was tested)
+or:
+```
+    go get github.com/jinks/passbleed
+```
+
+## Usage
+1. Export your KeePass database to CSV format with either [KeePass](http://keepass.info/) v2.35, [KeePassX](https://www.keepassx.org/) v2.0.3 or [KeepassXC](https://keepassxc.org/) v2.1.2
+2. Grab a copy of [sorted\_unique\_cf.txt](https://github.com/pirate/sites-using-cloudflare) (use the [master.zip](https://github.com/pirate/sites-using-cloudflare/archive/master.zip) to save some bandwidth)
+3. Run `./passbleed keepass.csv sorted_unique_cf.txt`
+
+## Caveats
+* All processing happens in RAM. On my machine it uses about 400 MB
+* __The exported CSV contains sensitive data.__ Put it on an encrypted disk and/or _securely_ delete it when you're done.
+
+