docs: clean up field usage

We currently have a mixture of several fields in our package docs. Between historic patterns and new workflows, each package may feature one or more of:

1. comment - a generic field for providing commentary on a package. This was previously always used to provide a link to a GPL sources tarball if required for a package
2. warning - usually used to indicate we've had to skip some sort of test or omit a piece of functionality in a module, due to incompatibility or known issues with riscv64 or our infrastructure
3. patched - a typically blank field used to signal that the package is built with one or more patches applied during the process

These are all somewhat redundant. I propose two to replace these:

1. gpl-sources - specify this with one or more links if we have to provide GPL source tarballs as part of the package builds
2. comment - anything else (notes about patching, skipping tests, etc.) goes here

@justeph @luhenry thoughts?

该 issue 未指定具体的文件或测试；首先定位目前使用 comment、warning 和 patched 的 package 文档字段。在迁移条目之前，确认建议的字段方案：使用 gpl-sources 表示 GPL 源代码链接，使用 comment 表示其他备注，然后验证不再存在旧字段的使用情况。