split docs/README so we have top-level README also

README.md

@@ -0,0 +1,39 @@
+# Zirgen Circuit Compiler
+
+Zirgen is a compiler for a domain-specific language, also called "zirgen",
+which creates arithmetic circuits for the RISC Zero proof system.
+
+For the most part, users of RISC Zero should be writing their zkApps in Rust
+and using our RISC-V zkVM rather than building them directly in Zirgen.
+Sometimes, however, it is necessary or desirable to write parts of an
+application as an arithmetic circuit to integrate directly with our proof system
+and achieve better performance. In fact, we have an upcoming version of the zkVM
+circuit written in Zirgen! Zirgen will make it possible to build accelerators
+for important parts of your applications, or even to build entire other VMs that
+integrate into the RISC Zero ecosystem through proof composition. With that said,
+it's still a work in progress and has quite a few rough edges.
+
+[Getting Started](zirgen/docs/01_Getting_Started.md)
+
+[Language Overview](zirgen/docs/02_Conceptual_Overview.md)
+
+## Included circuits
+
+* [The recursion circuit](/zirgen/circuit/recursion/)
+* [The RISC-V zkVM](/zirgen/circuit/rv32im/) 
+
+## Circom integration
+
+We also have an integration with Circom in the works -- this will make it
+possible to generate recursion circuit programs that verify witnesses for
+arbitrary Circom circuits. This can be found
+[here](/zirgen/compiler/tools/zirgen-r1cs.cpp).
+
+```mermaid
+graph TD;
+    A[Zirgen] --> B[Zirgen Compiler]
+    C[Circom] --> B
+    B --> D[Rust code]
+    B --> E[C++ code]
+    B --> F[Recursion VM predicates]
+```

zirgen/docs/01_Getting_Started.md

@@ -1,10 +1,10 @@
 # Getting Started
 
-We don't currently release Zirgen in any form, so it's only available through
-this repository. Assuming you've cloned and built things from this repo before,
-building Zirgen with Bazel is simple with the following command. Note, though,
-that this isn't strictly necessary, and that Bazel will automatically (re)build
-Zirgen if you use it to invoke the tests as well.
+We don't currently release Zirgen in any packaged form, so it's only available
+through this repository. Assuming you've cloned and built things from this repo
+before, building Zirgen with Bazel is simple with the following command. Note,
+though, that this isn't strictly necessary, and that Bazel will automatically
+(re)build Zirgen if you use it to invoke the tests as well.
 
 ```
 bazel build //zirgen/dsl:zirgen

zirgen/docs/README.md

@@ -3,17 +3,8 @@
 ## Introduction
 
 The Zirgen circuit language is a domain-specific language for writing arithmetic
-circuits for the RISC Zero proof system. For the most part, users of RISC Zero
-should be writing their zkApps in Rust and using our RISC-V zkVM rather than
-building them directly in Zirgen. However, sometimes it is necessary or
-desirable to write parts of an application as an arithmetic circuit to integrate
-directly with our proof system and achieve better performance. In fact, our zkVM
-itself is a circuit written in Zirgen! Zirgen makes it possible to build
-accelerators for important parts of your applications, or even to build entire
-other VMs that integrate into the RISC Zero ecosystem through proof composition.
-If that sounds like your goal, read on!
-
-So, what kinds of things can you build with Zirgen?
+circuits for the RISC Zero proof system. What kinds of things can you build
+with Zirgen?
 * zk accelerators (hashing, bigint operations, cryptographic primitives)
 * zkVMs
 * recursion circuits
@@ -22,5 +13,8 @@ So, what kinds of things can you build with Zirgen?
 Table of Contents:
 1. [Getting Started](01_Getting_Started.md)
 2. [Basic Concepts](02_Conceptual_Overview.md)
+3. [Building a Fibonacci Circuit](03_Building_a_Fibonacci_Circuit.md)
+4. [Components](04_Components.md)
+5. [Built-in Components](A1_Builtin_Components.md)
 
 [Next](01_Getting_Started.md)