docs: fix pbjs link in README (protobufjs#1578)

parent README doesn't have documentation about pbjs and it is moved to cli's README, update the link to the correct one.

README.md

@@ -82,7 +82,7 @@ The library supports CommonJS and AMD loaders and also exports globally as `prot
 
 Where bundle size is a factor, there are additional stripped-down versions of the [full library][dist-full] (~19kb gzipped) available that exclude certain functionality:
 
-* When working with JSON descriptors (i.e. generated by [pbjs](#pbjs-for-javascript)) and/or reflection only, see the [light library][dist-light] (~16kb gzipped) that excludes the parser. CommonJS entry point is:
+* When working with JSON descriptors (i.e. generated by [pbjs](cli/README.md#pbjs-for-javascript)) and/or reflection only, see the [light library][dist-light] (~16kb gzipped) that excludes the parser. CommonJS entry point is:
 
   ```js
   var protobuf = require("protobufjs/light");