Add documentation with Xcode IDE information

This is not meant to be an exhastive document, but rather a starting
point to help describe how to best use the Xcode IDE.

[email protected]

Bug: None
Change-Id: I821dba060353220c1f93cd49dd12dcd74aeaf790
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2188519
Reviewed-by: Mike Dougherty <[email protected]>
Commit-Queue: Mike Dougherty <[email protected]>
Cr-Commit-Position: refs/heads/master@{#766549}
diff --git a/docs/ios/build_instructions.md b/docs/ios/build_instructions.md
index 734f62d..5695097a 100644
--- a/docs/ios/build_instructions.md
+++ b/docs/ios/build_instructions.md
@@ -76,6 +76,8 @@
 builds, and generates an appropriate Xcode workspace
 (`out/build/all.xcworkspace`) as well.
 
+More information about [developing with Xcode](xcode_tips.md).
+
 You can customize the build by editing the file `$HOME/.setup-gn` (create it if
 it does not exist).  Look at `src/ios/build/tools/setup-gn.config` for
 available configuration options.
@@ -91,9 +93,11 @@
 (`autoninja` is a wrapper that automatically provides optimal values for the
 arguments passed to `ninja`.)
 
-Note: you need to run `setup-gn.py` script every time one of the `BUILD.gn`
-file is updated (either by you or after rebasing). If you forget to run it,
-the list of targets and files in the Xcode solution may be stale.
+Note: The `setup-gn.py` script needs to run every time one of the `BUILD.gn`
+files is updated (either by you or after rebasing). If you forget to run it,
+the list of targets and files in the Xcode solution may be stale. You can run
+the script directly or use either `gclient sync` or `gclient runhooks` which
+will run `setup-gn.py` for you as part of the update hooks.
 
 You can also follow the manual instructions on the
 [Mac page](../mac_build_instructions.md), but make sure you set the