Add a couple more readmes into the crates/

crates/agent/README.adoc

@@ -0,0 +1,7 @@
+= Otto Agent
+
+**Issue label:** `component/agent`
+
+This directory contains the re-usable code for implementing agents or
+block-scoped steps, essentially all the code necessary for invoking an Otto
+Step Library.

crates/models/README.adoc

@@ -0,0 +1,5 @@
+= Otto Models
+
+This crate is intended to contain very little actual logic, and instead
+contains the definitions for data models which must be serialized and
+deserialized between services in Otto.

crates/parser/README.adoc

@@ -1,6 +1,19 @@
 = Otto Parser
 
-The Otto Parser service is basically a parser engine that speaks HTTP. In the
-`src/` directory you will find the `.pest` grammar definition which outlines
-the Otto Pipeline syntax.
+**Issue label:** `components/parser`
 
+The Otto Parser is a link:https://pest.rs/[Pest] based parser which takes the
+Otto pipeline syntax and converts it into the Otto intermediate pipeline
+representation.
+
+In the `src/` directory you will find the `.pest` grammar definition which
+outlines the currently supported Otto Pipeline syntax.
+
+== Tests
+
+There are unit tests defined in `.rs` files inside of `src/`.
+
+The `test_data/` directory has two directories: `invalid` and `valid`. These
+files are used to validate basic parsing of the Otto pipeline syntax. No other
+validation is done on these files other than ensuring that they parse
+(`valid/`) or that they do not parse (`invalid/`).