Port #2610 to develop2 (#2676)

* add docs

* minor changes

reference/tools/files/basic.rst

@@ -280,5 +280,16 @@ Usage:
     from conan.tools.files import collect_libs
 
     def package_info(self):
-        self.cpp_info.libdirs = ["lib", "other_libdir"]  # Deafult value is 'lib'
-        self.cpp_info.libs = collect_libs(self)
+        self.cpp_info.libdirs = ["lib", "other_libdir"]  # Default value is 'lib'
+        self.cpp_info.libs = tools.collect_libs(self)
+
+For UNIX libraries starting with **lib**, like *libmath.a*, this tool will collect the
+library name **math**. Regarding symlinks, this tool will keep only the "most generic"
+file among the resolved real file and all symlinks pointing to this real file. For example
+among files below, this tool will select *libmath.dylib* file and therefore only append
+*math* in the returned list: 
+
+.. code-block:: shell
+
+    -rwxr-xr-x libmath.1.0.0.dylib lrwxr-xr-x libmath.1.dylib -> libmath.1.0.0.dylib
+    lrwxr-xr-x libmath.dylib -> libmath.1.dylib