Point to existing docs about include/exclude fields

Co-authored-by: Weihang Lo <weihanglo@users.noreply.github.com>

Author: sourcefrog

src/doc/man/cargo-package.md

@@ -33,14 +33,8 @@ stored in the `target/package` directory. This performs the following steps:
       about the current VCS checkout hash if available, as well as a flag if the
       worktree is dirty.
     - Symlinks are flattened to their target files.
-    - Subdirectories containing `Cargo.toml` are excluded, as they are assumed
-      to be separate packages.
-    - A `target` directory in the root of the package is excluded.
-    - Files and directories matching the `[include]` and `[exclude]` fields in
-      the manifest are included or excluded. Include patterns can override the
-      following rules.
-    - Files that are ignored by VCS are excluded.
-    - Unix hidden files and directories (starting with `.`) are excluded.
+    - Files and directories are included or excluded based on rules mentioned in
+      [the `[include]` and `[exclude]` fields](../reference/manifest.html#the-exclude-and-include-fields).
 
 3. Extract the `.crate` file and build it to verify it can build.
     - This will rebuild your package from scratch to ensure that it can be