Fix comments in GN standalone docs.

The GN standalone docs appear to have had from day one a placeholder
for a section that was never written. This CL deletes that placeholder
and tweaks the wording above it to hopefully make a bit more sense.

R=thakis@chromium.org, brettw@chromium.org

Review-Url: https://codereview.chromium.org/2801733004
Cr-Original-Commit-Position: refs/heads/master@{#462604}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 707f1a623b690a870f6378ccf074b51cdaad9556
diff --git a/tools/gn/docs/standalone.md b/tools/gn/docs/standalone.md
index faeb426..81dd896 100644
--- a/tools/gn/docs/standalone.md
+++ b/tools/gn/docs/standalone.md
@@ -35,7 +35,10 @@
 your subproject rather than for all of Chrome. This could be an
 advantage or a disadvantage.
 
-If you would rather avoid using this file, you can use the command-line
-flags `--root` and `--dotfile` to set these values.
+If you are in a directory with such a file and you want to not use it
+(e.g., to do the full Chrome build instead), you can use the command-line
+flags `--root` and `--dotfile` to set the values you want.
 
-# How the standalone and Chrome builds interact
+If you want a completely standalone build that has nothing to do w/ Chrome
+and doesn't use Chrome's //build files, you can look at an example in
+[//tools/gn/example](../example).