Document Lookup Contribution Process

[keithwill]

There is no documentation on how to add a new collection to TrieHard, or how to wrap a lookup alternative implementation.

We need a markdown document that contains guidance on:

• Which project to add an implementation to (PrefixLookup vs Alternatives)
• Licensing concerns of adding an implementation to the PrefixLookup project (MIT compatible only)
• Implementing the IPrefixLookup interface
• How to add the implementation to the unit test suite
• How to add the implementation to the benchmark suite