gemspec: remove has_rdoc

Signed-off-by: Masahiro Nakagawa <[email protected]>

Author: repeatedly

fluent-plugin-sql.gemspec

@@ -9,7 +9,6 @@ Gem::Specification.new do |gem|
   gem.version     = File.read("VERSION").strip
   gem.authors     = ["Sadayuki Furuhashi"]
   gem.email       = "[email protected]"
-  gem.has_rdoc    = false
   #gem.platform    = Gem::Platform::RUBY
   gem.files       = `git ls-files`.split("\n")
   gem.test_files  = `git ls-files -- {test,spec,features}/*`.split("\n")