Add explainations for every layer of file types

Author: trcrsired

docs/docs/03.pointer/index.html

@@ -136,7 +136,7 @@ <h2>Handles</h2>
     FILE *f{stdout};
 
     println(
-        "POSIX fd:", handlevw(fd), "\n",
+        "POSIX fd:", handlevw(fd), "\n"
         "FILE* handle:", handlevw(f)
     );
 }