Update the version in docs to next release

This also accounts for dagger.io/dagger/core split introduced in
https://github.com/dagger/dagger/pull/1866

We should hold this merge until we are ready to cut the release,
otherwise links & some instructions will be broken until we release
v0.2.3.

Even though I would have preferred to have docs/update-version.sh in
Dagger, this is the quickest thing for now.

Related to https://github.com/dagger/dagger/issues/1854

Signed-off-by: Gerhard Lazu <gerhard@lazu.co.uk>

docs/update-version.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+set -ex
+
+if ! sed --version | grep "GNU"
+then
+  echo "Please install GNU sed, a.k.a. gnused"
+  exit 1
+fi
+
+sed --in-place --regexp-extended --expression \
+  's/v'"${DAGGER_VERSION_FROM:-0.2.0}"'/v'"${DAGGER_VERSION_TO:-0.2.3}"'/g' \
+  ./*/*.md