Remove .envrc and show an example in .envrc.sample

The .envrc file is used by direnv to load the environment variables and
having this file in the repository can cause problems when the user has
already one in his home directory.

Moreover this file automatically loads silently the environment
variables from .env.sample bypassing the explicit "direnv allow" that
usually needed with .envrc which can be a potential security issue.

This is still a useful file and to know about for contributors so we
keep the sample file in .envrc.sample and let user copy it to .envrc if
they want to use it.

Signed-off-by: Chmouel Boudjnah <chmouel@redhat.com>

Author: chmouel

.env.sample

@@ -0,0 +1,7 @@
+# shellcheck shell=bash
+# This is an example of a .envrc file for use with direnv
+#
+# See https://direnv.net/#getting-started for more information on how to get
+# started with direnv
+export GOMAXPROCS=6
+export KO_DOCKER_REPO=gcr.io/tektoncd/pipeline