v3.0.1: the direnv template now exports its variables

Patch release. No change to the tool's behaviour, outputs or contracts.

Fixed

• .envrc.example now exports its variables. The template shipped in v3.0.0 had lines such as # DNSRESOLVER_TIMEOUT=1. direnv evaluates .envrc as shell, so uncommenting one as written set an unexported variable that never reached the tool. Every example line is now # export DNSRESOLVER_X=default, and the README says to keep the export. A new test uncomments the whole template, sources it in bash and checks that every variable the code reads is exported.

If you copied the v3.0.0 template, copy it again (cp .envrc.example .envrc && direnv allow) or add export to the lines you uncommented.

Everything else is unchanged from v3.0.0, including its breaking changes if you are upgrading from v2.