Add deprecation notes regarding legacy gitbook toolchain, as links are broken
Change-Id: If85ed8f5d6485b3124a1ed9aed389a09860de3e4
diff --git a/developer/contribute_to_the_docs.md b/developer/contribute_to_the_docs.md
index 8318116..0b9c2de 100644
--- a/developer/contribute_to_the_docs.md
+++ b/developer/contribute_to_the_docs.md
@@ -1,8 +1,8 @@
# Contribute to the documentation
-> This tutorial assumes you already have [cloned the code](./getting_the_code.md),
-> [NodeJs](https://nodejs.org/en/) and the [Gitbook Toolchain](https://toolchain.gitbook.com/)
-> are installed.
+> This tutorial assumes you already have [cloned the
+> code](./getting_the_code.md), [NodeJs](https://nodejs.org/en/) and the legacy
+> Gitbook Toolchain (deprecated, docs unavailable) are installed.
From a terminal window navigate to the documentation root:
diff --git a/overview.md b/overview.md
index 1a16dfb..f0d1ba8 100644
--- a/overview.md
+++ b/overview.md
@@ -51,7 +51,7 @@
## Making Changes to this Document
The [http://guide.opencord.org](http://guide.opencord.org) website is built
-using the [GitBook Toolchain](https://toolchain.gitbook.com/), with the
+using the legacy GitBook Toolchain (deprecated, docs unavailable), with the
documentation root in
[docs](https://github.com/opencord/docs/blob/{{ book.branch }}) in a
checked out source tree. It is build with `make`, and requires that `gitbook`,