* error.c: RDoc for subclasses of Exception. [ruby-core:28394]

* cont.c: ditto

* enumerator.c: ditto

* io.c: ditto

* math.c: ditto

* numeric.c: ditto

* proc.c: ditto

* re.c: ditto

* thread.c: ditto

* transcode.c: ditto. Thanks to Run Paint for some of the documentation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@27673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -9585,6 +9585,41 @@ rb_get_argv(void)
     return ARGF.argv;
 }
 
+/*
+ * Document-class: IOError
+ *
+ * Raised when an IO operation fails.
+ *
+ *    File.open("/etc/hosts") {|f| f << "example"}
+ *      #=> IOError: not opened for writing
+ *
+ *    File.open("/etc/hosts") {|f| f.close; f.read }
+ *      #=> IOError: closed stream
+ *
+ * Note that some IO failures raise +SystemCallError+s and these are not
+ * subclasses of IOError:
+ *
+ *    File.open("does/not/exist")
+ *      #=> Errno::ENOENT: No such file or directory - does/not/exist
+ */
+
+/*
+* Document-class: EOFError
+*
+ * Raised by some IO operations when reaching the end of file. Many IO
+ * methods exist in two forms,
+ *
+ * one that returns +nil+ when the end of file is reached, the other
+ * raises EOFError +EOFError+.
+ *
+ * +EOFError+ is a subclass of +IOError+.
+ *
+ *    file = File.open("/etc/hosts")
+ *    file.read
+ *    file.gets     #=> nil
+ *    file.readline #=> EOFError: end of file reached
+ */
+
 /*
  * Document-class:  ARGF
  *