[dev.boringcrypto] add README.boringcrypto.md, update VERSION

Change-Id: I415fcc23b62666d78aed3ddc7d2731127c810be3
Reviewed-on: https://go-review.googlesource.com/55471
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>

README.boringcrypto.md

@@ -0,0 +1,18 @@
+# dev.boringcrypto branch
+
+We have been working inside Google on a fork of Go that uses
+BoringCrypto (the core of [BoringSSL](https://boringssl.googlesource.com/boringssl/)) for various crypto primitives, in
+furtherance of some [work related to FIPS 140-2](http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp2964.pdf). We have heard that
+some external users of Go would be interested in this code as well, so
+I intend to create a new branch dev.boringcrypto that will hold
+patches to make Go use BoringCrypto.
+
+Unlike typical dev branches, we do not intend any eventual merge of
+this code into the master branch. Instead we intend to maintain in
+that branch the latest release plus BoringCrypto patches. In this
+sense it is a bit like dev.typealias holding go1.8+type alias patches.
+
+To be clear, we are not making any statements or representations about
+the suitability of this code in relation to the FIPS 140-2 standard.
+Interested users will have to evaluate for themselves whether the code
+is useful for their own purposes.