Add info on layout of sbws repo

GH: closes #100

README.md

@@ -80,6 +80,21 @@ The sbws documentation can be found at
 [this onion service](http://d7pxflytfsmz6uh3x7i2jxzzwea6nbpmtsz5tmfkcin5edapaig5vpyd.onion/)
 ([v2](http://sdmb3rfvp3wadu6y.onion/)).
 
+## Layout of the sbws repo
+
+- `docs/` the source of the sbws documentation website.
+- `sbws/` the source code for sbws.
+- `sbws/core/` each file contains code specific to a single sbws command.
+- `sbws/lib/` complex data structures and classes useful to one or more sbws
+  commands. If you're making a new class, it probably belongs here.
+- `sbws/util/` simplier, "make life easier" collections of functions.
+- `scripts/maint/` scripts for **maint**aining sbws and doing administrative
+  things like regenerating the website or updating the AUTHORS file.
+- `scripts/tools/` misc. scripts for users of sbws.
+- `tests/testnets/` scripts and code for running mini Tor networks locally and
+  performing integration tests with them.
+- `tests/` unit tests executed with `pytest` or `tox`.
+
 ### Build HTML documentation
 
     pip install -e .[doc]