Remove obsolete hacking.md

Change-Id: I0ea42fc0325d9fd432136094a6ac0149a0f470a9
Reviewed-on: https://gn-review.googlesource.com/2760
Reviewed-by: Brett Wilson <brettw@chromium.org>
Commit-Queue: Brett Wilson <brettw@chromium.org>
diff --git a/README.md b/README.md
index 5c98d1f..cc981fa 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,8 @@
 # GN
 
 GN is a meta-build system that generates build files for
-[Ninja](https://ninja-build.org).
+[Ninja](https://ninja-build.org). There is documentation in
+[docs/](https://gn.googlesource.com/gn/+/master/docs/).
 
 ## Getting started
 
@@ -9,6 +10,8 @@
     cd gn
     python build/gen.py
     ninja -C out
+    # To run tests:
+    out/gn_unittests
 
 On Windows, it is expected that `cl.exe`, `link.exe`, and `lib.exe` can be found
 in `PATH`, so you'll want to run from a Visual Studio command prompt, or
diff --git a/docs/hacking.md b/docs/hacking.md
deleted file mode 100644
index be3f132..0000000
--- a/docs/hacking.md
+++ /dev/null
@@ -1,23 +0,0 @@
-# Hacking on the GN binary itself
-
-## Building GN itself
-
-GN is part of the Chromium tree, in [//tools/gn/](../). If you have a
-Chromium checkout, you already have the source and you can do `ninja -C
-out/Debug gn` to build it.
-
-To build gn using gn, run (in the root `src` directory):
-
-```
-gn gen out/Default
-ninja -C out/Default gn
-```
-
-Change `out/Default` as necessary to put the build directory where you
-want.
-
-## Running GN's unit tests
-
-```
-ninja -C out/Default gn_unittests && out/Default/gn_unittests
-```