split the file I/O topic

Author: vladak

docs/syllabus.html

@@ -62,13 +62,14 @@ <h1>Unix programming in C syllabus</h1>
 library calls
 return values
 err API
-file API
+file API, up to stat()
 </pre>
 <!--[slajdy 49-53, 80-101]</em> -->
 </p>
 
 <p><b>4. lecture</b><br>
 <pre>
+file API, till the end
 /etc/passwd, /etc/group
 access rights
 user/group identification