Re-run `gn help --markdown all > tools/gn/docs/reference.md`.

This should've been part of https://chromium-review.googlesource.com/c/chromium/src/+/1020010

Bug: 835319
Change-Id: Ibad6a9b3f686ed8305ffc77c866917124fef9ba5
Reviewed-on: https://chromium-review.googlesource.com/1021597
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#552387}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: a8fe0c1bdb12ce92c841d4527b54ae3e023cb590

tools/gn/docs/reference.md

diff --git a/tools/gn/docs/reference.md b/tools/gn/docs/reference.md
index 902adc0..47c743e 100644
--- a/tools/gn/docs/reference.md
+++ b/tools/gn/docs/reference.md
@@ -2209,6 +2209,13 @@
   context of more than one toolchain it is recommended to specify an
   explicit toolchain when defining and referencing a pool.
 
+  A pool named "console" defined in the root build file represents Ninja's
+  console pool. Targets using this pool will have access to the console's
+  stdin and stdout, and output will not be buffered. This special pool must
+  have a depth of 1. Pools not defined in the root must not be named "console".
+  The console pool can only be defined for the default toolchain.
+  Refer to the Ninja documentation on the console pool for more info.
+
   A pool is referenced by its label just like a target.
 ```