all: link to the "state of x/text" video

Change-Id: I1eedba96d30ee1587da6408b55b0a7f5b8c1463a
Reviewed-on: https://go-review.googlesource.com/91835
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/doc.go b/doc.go
index a48e284..2e19a41 100644
--- a/doc.go
+++ b/doc.go
@@ -7,6 +7,9 @@
 // text is a repository of text-related packages related to internationalization
 // (i18n) and localization (l10n), such as character encodings, text
 // transformations, and locale-specific text handling.
+//
+// There is a 30 minute video, recorded on 2017-11-30, on the "State of
+// golang.org/x/text" at https://www.youtube.com/watch?v=uYrDrMEGu58
 package text
 
 // TODO: more documentation on general concepts, such as Transformers, use