Minor rdoc patch for sha2.rb

Hi,

The :nodoc: tag must go to the right of the def, not above it:

--- sha2.orig   2007-04-04 18:16:21.000000000 -0600
+++ sha2.rb     2007-04-04 18:19:37.000000000 -0600
@@ -34,14 +34,12 @@
        @bitlen = bitlen
      end

-    # :nodoc:
-    def reset
+    def reset # :nodoc:
        @sha2.reset
        self
      end

-    # :nodoc:
-    def update(str)
+    def update(str) # :nodoc:
        @sha2.update(str)
        self
      end
@@ -60,13 +58,11 @@
        @sha2.digest_length
      end

-    # :nodoc:
-    def initialize_copy(other)
+    def initialize_copy(other) # :nodoc:
        @sha2 = other.instance_eval { @sha2.clone }
      end

-    # :nodoc:
-    def inspect
+    def inspect # :nodoc:
        "#<%s:%d %s>" % [self.class.name, @bitlen, hexdigest]
      end
    end