Allow users to specify their adapter in the docs

[epompeii]

Currently the bencher mock subcommands is used throughout the docs as a placeholder for a users own benchmark command. Allow a user to select their preferred adapter and the. have the docs update accordingly.

For example, if the rust_criterion adapter was selected, the docs would show cargo bench.

[mikenye]

For Go, please feel free to use these:

• On PR: https://github.com/mikenye/geom2d/blob/main/.github/workflows/bencher_pr.yaml
• On Push to main: https://github.com/mikenye/geom2d/blob/main/.github/workflows/bencher_push.yaml