added megamash docs (#91)

This simply updates megamash documentation

README.md

@@ -76,6 +76,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+- Updated megamash documentation to be more specific. [#91](https://github.com/Koeng101/dnadesign/pull/91)
 - Adds automatic python documentation generation. [#88](https://github.com/Koeng101/dnadesign/pull/88)
 - Adds genbank parsing to python package. Release version 0.1.5 of dnadesign python. [#87](https://github.com/Koeng101/dnadesign/pull/87)
 - Adds fastq parsing to python package. Releases version 0.1.4 of dnadesign python. [#86](https://github.com/Koeng101/dnadesign/pull/86)

lib/align/megamash/megamash.go

@@ -5,6 +5,12 @@ Megamash is an algorithm developed by Keoni Gandall to find templates from
 sequencing reactions. For example, you may have a pool of amplicons, and need
 to get a count of how many times each amplicon shows up in a given sequencing
 reaction.
+
+Megamash takes all unique kmers of a given sequence among all other sequences
+in a pool, and uses those to distinguish how close a given target is to that
+particular sequence. This does not work if there are no unique kmers within a
+sequence: this can often happen in combinatorial libraries. For sequences like
+that, it is better to look to a different algorithm.
 */
 package megamash