Add more documentation for Gem::Specification

doc/mrbgems/README.md

@@ -98,6 +98,37 @@ The mrbgems build process will use this specification to compile Object and Ruby
 files. The compilation results will be add to *lib/libmruby.a*. This file is used
 by tools like `mruby` and `mirb` to empower the GEM functionality.
 
+The following properties can be set inside of your `MRuby::Gem::Specification` for
+information purpose:
+
+* spec.license or spec.licenses (License [String] or Licenses [Array] for this GEM)
+* spec.author or spec.authors (Developer names author [String] authors [Array])
+* spec.version (Current Version [String]
+* spec.description (Detailed description [String])
+* spec.summary (Short summary [String])
+* spec.homepage (Homepage [String])
+* spec.requirements
+
+It is required for every GEM to have a license and an author!
+
+In case your GEM is depending on other GEMs please use
+`spec.add_dependency(gem, requirements)` like:
+
+	MRuby::Gem::Specification.new('c_and_ruby_extension_example') do |spec|
+	  spec.license = 'MIT'
+	  spec.authors = 'mruby developers'
+
+	  # add GEM dependency parser.
+          # Version has to be between 1.0.0 and 1.5.2
+	  spec.add_dependency('parser', '> 1.0.0', '< 1.5.2')
+	end
+
+The usage of versions is optional.
+
+__ATTENTION__
+The dependency system is currently (May 2013) under development and doesn't check
+or resolve dependencies for now!
+
 In case your GEM has more complex build requirements you can use
 the following options additionally inside of your GEM specification: