library "not found in package" hint recommends --path "lib/", which lists nothing #9916

Problem

When library <L> --package P can't find <L>, it prints:

Error: Library 'Nope' not found in package.
Use 'dotnet-inspect package <name> --path "lib/"' to list available libraries.

--path "lib/" is a directory selector. A trailing slash selects only the immediate files in that directory (PackageFileLister.cs:120-125). That is by design, but lib/ normally holds only framework subdirectories, so the suggested command lists nothing:

$ dotnet-inspect package EntityFramework@6.4.4 --path lib/
Note: 1 matched section has no data: Files.
# EntityFramework

The hint appears in two places, LibraryCommand.cs:5245 (the --tfm all branch) and LibraryCommand.cs:5260 (the named-Library search).

Fix

Point the hint at a command that lists the package's library assets, for example:

$ dotnet-inspect package EntityFramework@6.4.4 -S Files --lib
EntityFramework 6.4.4 (NuGet)
└─ lib
   ├─ net40
   │  ├─ EntityFramework.SqlServer.dll
   ...

The --tfm all branch at line 5245 retires under #9915/#9833, because library ... --tfm all will fail before acquisition. Only the hint at line 5260 then needs fixing.