adderall.dsl: Use better names for our symbols

Use bothᵍ (or bothg) instead of both, and =ᵒ (or =o) instead of eq.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
adderall.dsl: Implement eitherᵍ

The eitherᵍ goal takes two other goals, and succeeds if any of them
succeed.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
README.md: Add a short example

Signed-off-by: Gergely Nagy <algernon@balabit.hu>