[Docs] adding link to closure tags

docs/closure_compilation.md

 # Closure Compilation
 
 ## I just need to fix the compile!
 
 To locally run closure compiler like the bots, do this:
 
 ```shell
 cd $CHROMIUM_SRC
 # sudo apt-get install openjdk-7-jre # may be required
 GYP_GENERATORS=ninja tools/gyp/gyp --depth . \
 third_party/closure_compiler/compiled_resources.gyp
 ninja -C out/Default
 ```
 
 ## Background
 
 In C++ and Java, compiling the code gives you _some_ level of protection against
 misusing variables based on their type information. JavaScript is loosely typed
 and therefore doesn't offer this safety. This makes writing JavaScript more
 error prone as it's _one more thing_ to mess up.
 
 Because having this safety is handy, Chrome now has a way to optionally
 typecheck your JavaScript and produce compiled output with
 [Closure Compiler](https://developers.google.com/closure/compiler/).
+The type information is
+[annotated in comment tags](https://developers.google.com/closure/compiler/docs/js-for-compiler)
+that are briefly described below.
 
 See also:
 [the design doc](https://docs.google.com/a/chromium.org/document/d/1Ee9ggmp6U-lM-w9WmxN5cSLkK9B5YAq14939Woo-JY0/edit).
 
 ## Assumptions
 
 A working Chrome checkout. See here:
 http://www.chromium.org/developers/how-tos/get-the-code
 
 ## Typechecking Your Javascript
@@ skipping 234 matching lines @@
           'jscomp_error=duplicate',
           'jscomp_error=misplacedTypeAnnotation',
         ],
         'disabled_closure_args': [], # remove the disabled closure args for more strict compilation
       },
       'includes': ['../third_party/closure_compiler/compile_js.gypi'],
     },
   ],
 }
 ```