want error message for non-pascal-case type names to suggest `schemars` interpolation for generic types

I was recently tripped up by the discovery that the default schema names that schemars generates for generic types are not PascalCase and are therefore rejected by openapi-lint (and opened #28). After doing some digging, I discovered that this was previously discussed in #14, and can be resolved using the #[schemars(rename = "...")] attribute, with the generic type parameter interpolated into a format-string-like syntax. See, for example, https://github.com/oxidecomputer/omicron/commit/775f9aa5c63382887092d852452f3719084fba9f.

Currently, though, the lint output for this only suggests the #[serde(rename = "...")] attribute, and not the schemars version; and as demonstrated by my flailing in the replies to #28, this doesn't solve the problem:

       error: Generated OpenAPI document for API "nexus-lockstep" version 0.0.1 is not valid: OpenAPI document
              validation failed:
              The type "Setting_for_Boolean" has a name that is not PascalCase; to rename it add #[serde(rename
              = "SettingForBoolean")]
              For more info, see https://github.com/oxidecomputer/openapi-lint#naming
              The type "Setting_for_NonZeroU32" has a name that is not PascalCase; to rename it add
              #[serde(rename = "SettingForNonZeroU32")]
              For more info, see https://github.com/oxidecomputer/openapi-lint#naming

It would be nice if the lint itself, or at least the docs it links to, suggested the correct thing. For instance, it could look for the _for_ pattern in a schema name and say something like:

       error: Generated OpenAPI document for API "nexus-lockstep" version 0.0.1 is not valid: OpenAPI document
              validation failed:
              The type "Setting_for_Boolean" has a name that is not PascalCase; to rename it add #[serde(rename
              = "SettingForBoolean")]
       note: This looks like it might have been a generic type. Use the `#[schemars(rename = "...")]`
             attribute and interpolate the generic type parameter into the format string.

or something

Start with the naming-rule validation that emits the shown non-PascalCase error, then review issues #14 and #28 and the linked openapi-lint naming documentation. Compare the current serde suggestion with schemars generic-name interpolation. Done means the lint or its linked documentation clearly points users to the schemars rename approach for generic types.