Add links to documentation when errors occur

[dgageot]

While creating my builder with pack create-builder, I saw this error:

ERROR: validating buildpacks: buildpack my-stack.java@0.0.1 (Buildpack API version 0.1) is incompatible with lifecycle 0.4.0 (Buildpack API version 0.2)

However, I couldn't find any documentation that explains that api field should be set in buildpack.toml. If such documentation exists or is later on created, it would be nice to point at it in the warning.

[ekcasey]

The only reference in the docs currently is here https://buildpacks.io/docs/create-buildpack/building-blocks-cnb/.

It's purpose isn't well described, nor do we have a good documentation around which version of the buildpack interface / set of specified features are represented by buildpack API 0.1 vs 0.2. We should improve this.

[jromero]

However, I couldn't find any documentation that explains that api field should be set in buildpack.toml

Created buildpacks/docs#66 to address this.

If such documentation exists or is later on created, it would be nice to point at it in the warning.

This is something we don't currently do but it's an interesting idea. I personally like it. I know of certain CLI tools that do it and it works really well. A concern I can see being voiced would be broken links. We'd have to be more careful about changes to documentation locations or provide redirects when we do make changes. That seems like a minor set back to what the benefits could be.