[docs] Fix typo 'is' => 'it'

Change-Id: Iec2c96a507593f07b8059f871956fbb3f92876cb
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/4900
Reviewed-by: Brett Wilson <brettw@google.com>
Commit-Queue: Scott Graham <scottmg@chromium.org>

docs/reference.md

diff --git a/docs/reference.md b/docs/reference.md
index be887b9..b4d7596 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -1271,7 +1271,7 @@
     script = "idl_processor.py"
     sources = [ "foo.idl", "bar.idl" ]
 
-    # Our script reads this file each time, so we need to list is as a
+    # Our script reads this file each time, so we need to list it as a
     # dependency so we can rebuild if it changes.
     inputs = [ "my_configuration.txt" ]
 

tools/gn/functions_target.cc

diff --git a/tools/gn/functions_target.cc b/tools/gn/functions_target.cc
index be02fc4..a0690ab 100644
--- a/tools/gn/functions_target.cc
+++ b/tools/gn/functions_target.cc
@@ -221,7 +221,7 @@
     script = "idl_processor.py"
     sources = [ "foo.idl", "bar.idl" ]
 
-    # Our script reads this file each time, so we need to list is as a
+    # Our script reads this file each time, so we need to list it as a
     # dependency so we can rebuild if it changes.
     inputs = [ "my_configuration.txt" ]