Update src/README.txt. Closes #2147

Author: brson

src/README.txt

@@ -1,28 +1,43 @@
-This is preliminary version of the Rust compiler.
+This is preliminary version of the Rust compiler, libraries and tools
 
 Source layout:
 
 rustc/             The self-hosted compiler
 
-cargo/             The package manager
-
 libcore/           The core library (imported and linked by default)
 libstd/            The standard library (slightly more peripheral code)
-
-rustllvm/          LLVM support code
+librustsyntax/     The Rust parser and pretty-printer
 
 rt/                The runtime system
 rt/rust_*.cpp      - The majority of the runtime services
 rt/isaac           - The PRNG used for pseudo-random choices in the runtime
 rt/bigint          - The bigint library used for the 'big' type
 rt/uthash          - Small hashtable-and-list library for C, used in runtime
-rt/libuv           - The library used for async IO in the runtime
-rt/{sync,util}     - Small utility classes for the runtime.
+rt/sync            - Concurrency utils
+rt/util            - Small utility classes for the runtime.
+rt/vg              - Valgrind headers
+rt/msvc            - MSVC support
 
 test/              Testsuite
 test/compile-fail  - Tests that should fail to compile
 test/run-fail      - Tests that should compile, run and fail
 test/run-pass      - Tests that should compile, run and succeed
 test/bench         - Benchmarks and miscellanea
+test/pretty        - Pretty-printer tests
+test/auxiliary     - Dependencies of tests
+
+compiletest/       The test runner
+
+cargo/             The package manager
+
+rustdoc/           The Rust API documentation tool
+
+llvm/              The LLVM submodule
+
+libuv/             The libuv submodule
+
+rustllvm/          LLVM support code
+
+fuzzer/            A collection of fuzz testers
 
-Please be gentle, it's a work in progress.
+etc/               Scripts, editor support, misc