Add the runrom crate and the vnf library

The vnf library supports the runrom crate and they both combined enable
users to "run" a ROM file. This is basically an emulator, but with two
key differences:

1. It is to be run programatically. That is, you are not expected to
   play games with this, but to run code by steps, start at a given
   address, run a function, etc.
2. It is headless: there are no graphics displayed on screen, nor sound
   being delivered.

Thus, the target for both these things are developers, not players. This
way developers can validate code paths without needing a full blown
emulator. You can write tests with this and be able to run some checks
as part of your testing infrastructure.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/README.md b/README.md
index 80f171d..8537eb7 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,15 @@ will invoke `nasm` with more pedantic features like its address sanitizer.
 information about it. Read more about it in
 [./crates/readrom/README.md](./crates/readrom/README.md).
 
+## `runrom`
+
+`runrom` is an NES/Famicom emulator that doesn't attempt to run a ROM
+graphically. Instead, it just runs code and exposes the data on memory,
+registers, etc. for a given run. Thus, `runrom` is a tool to run an NES/Famicom
+programatically, so developers can use it to test their ROM files under certain
+conditions. Read more about it in
+[./crates/runrom/README.md](./crates/runrom/README.md).
+
 ## License
 
 This repository holds two licenses, as you can also note on the `Cargo.toml`