Update the basic readme.

README.md

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 # tarmux
 A tool to multiplex and demultiplex streams from pipes to tar and back again.
+
+Tarmux attempts to solve the problem of handling streamed data where there
+is insufficient temporary space on disk to hold the data, as is forced by
+tar.
+
+In the simplest invocation, tarmux takes a stream from stdin, and creates
+a tar file consisting of sequential numbered file fragments one after the
+other. This can be reversed by the tardemux tool, which will untar the
+fragments and reassemble the stream to stdout.
+
+The tardemux tool only reads a single tar stream before exiting. This allows
+multiple streams to be concatenated in the same stream, and then split out
+by each invocation of tardemux.
+
+# about tarmux
+
+Tarmux is written for speed in portable C, and is tested on MacOSX, Redhat
+and Ubuntu. Tar mux depends on libarchive http://www.libarchive.org/.
+Packaging is available for RPM and Debian/Ubuntu systems.