Update runtime files.

runtime/doc/if_pyth.txt

@@ -168,11 +168,15 @@ vim.eval(str)						*python-eval*
 	- a dictionary if the Vim expression evaluates to a Vim dictionary
 	Dictionaries and lists are recursively expanded.
 	Examples: >
+	    :" value of the 'textwidth' option
 	    :py text_width = vim.eval("&tw")
-	    :py str = vim.eval("12+12")		# NB result is a string! Use
-						# string.atoi() to convert to
-						# a number.
-
+	    :
+	    :" contents of the 'a' register
+	    :py a_reg = vim.eval("@a") 
+	    :
+	    :" Result is a string! Use string.atoi() to convert to a number.
+	    :py str = vim.eval("12+12")
+	    :
 	    :py tagList = vim.eval('taglist("eval_expr")')
 <	The latter will return a python list of python dicts, for instance:
 	[{'cmd': '/^eval_expr(arg, nextcmd)$/', 'static': 0, 'name': ~