Update BRANCHES.md for 3.2.0 release

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/BRANCHES.md b/BRANCHES.md
index 3aca159..6240023 100644
--- a/BRANCHES.md
+++ b/BRANCHES.md
@@ -12,11 +12,6 @@
 - One or more long-time support (LTS) branches: these only get bug fixes and
   security fixes. Currently, the only supported LTS branch is:
   [`mbedtls-2.28`](https://github.com/Mbed-TLS/mbedtls/tree/mbedtls-2.28).
-- For a short time we also have the previous LTS, which has recently ended its
-  support period,
-  [`mbedtls-2.16`](https://github.com/Mbed-TLS/mbedtls/tree/mbedtls-2.16).
-  This branch will move into the `archive` namespace around the time of
-  the next release.
 
 We retain a number of historical branches, whose names are prefixed by `archive/`,
 such as [`archive/mbedtls-2.7`](https://github.com/Mbed-TLS/mbedtls/tree/archive/mbedtls-2.7).