Add more explanation and a note about features

README.md

@@ -21,9 +21,29 @@ import {
 
 ## Why
 
-The BDD-style library included as part of deno_std is slow and blocks adding
+The BDD-style library included as part of `deno_std` is slow and blocks adding
 more tests in the global scope by running groups of tests too-soon. This wrapper
 is completely written to allow all groups of tests to be cached as they are
 discovered and then only ran once the top-level `describe` is complete.
 
+Additionally, the internal `TestSuiteInternal` class and exported function call
+implementation are overly complex in `deno_std`. Attempting to untangle how the
+code works, I found the the concept of discovering test suites was tightly
+coupled to how the test suites would be grouped and also to the global test
+suite context. These are highly independent abstractions and I felt they should
+be loosely coupled. I have attempted to achieve a more loos-coupling, so that
+future changes to the abstractions of test suite, test suite groups, and the
+global context will be more easily acheived.
+
 This fixes an issue with running BDD-style tests under `denoland/dnt`.
+
+## Note
+
+This library does not fully-implement the BDD-style API from `deno_std`. Below
+is a list of known missing API features, which I expect to flesh out over the
+next few months I need the features.
+
+- Options bag for `describe` and `it` calls do not extend
+  `interface Deno.TestDefinition`
+- Function `describe` does not provide `describe.only` or `describe.ignore`
+- Function `it` does not provide `it.only` or `it.ignore`