[ios blink] Adjust documentation

Add a few more fields to the build instructions for ios_blink.

Change-Id: I18c4d8d0b76062cac63ae1852632db8e2ad6c4e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6323123
Reviewed-by: Rohit Rao <[email protected]>
Commit-Queue: Dave Tapuska <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1427752}
diff --git a/docs/ios/build_instructions.md b/docs/ios/build_instructions.md
index d0bc14a..2d41c9ff 100644
--- a/docs/ios/build_instructions.md
+++ b/docs/ios/build_instructions.md
@@ -286,11 +286,16 @@
 
 The iOS build supports compiling the blink web platform. To compile blink
 set a gn arg in your `.setup-gn` file. Note the blink web platform is
-experimental code and should only be used for analysis.
+experimental code and should only be used for analysis. We currently
+disable V8 pointer compression and the caged heap because of virtual
+memory allocation issues experienced on physical iOS devices.
 
 ```
 [gn_args]
 use_blink = true
+ios_content_shell_bundle_identifier="REPLACE_YOUR_BUNDLE_IDENTIFIER_HERE"
+cppgc_enable_caged_heap = false
+v8_enable_pointer_compression = false
 ```
 Note that only certain targets support blink. `content_shell` being the
 most useful.