Provide a way to store additional package meta information; Sync data with awesome-cpp

[Fleischner]

fffaraz/awesome-cpp#789
#6154

• vcpkg: choose which information belongs into the port file
• vcpkg: choose a way to store additional meta information (eg: build status, operating system support, ...)

[myd7349]

How about adding a Topic/Category/Keywords field? For example, all logging libraries in vcpkg can be tagged with Logging.