tool: add descriptions and fix typos

* tool/asm_parse.rb: add description
* tool/change_maker.rb: ditto
* tool/downloader.rb: ditto
* tool/eval.rb: ditto
* tool/expand-config.rb: ditto
* tool/extlibs.rb: ditto
* tool/fake.rb: ditto
* tool/file2lastrev.rb: ditto
* tool/gem-unpack.rb: ditto
* tool/gen_dummy_probes.rb: ditto
* tool/gen_ruby_tapset.rb: ditto
* tool/generic_erb.rb: ditto
* tool/id2token.rb: ditto
* tool/ifchange: ditto
* tool/insns2vm.rb: ditto
* tool/instruction.rb: ditto
* tool/jisx0208.rb: ditto
* tool/merger.rb: ditto
* tool/mkrunnable.rb: ditto
* tool/node_name.rb: ditto
* tool/parse.rb: ditto
* tool/rbinstall.rb: ditto
* tool/rbuninstall.rb: ditto
* tool/rmdirs: ditto
* tool/runruby.rb: ditto
* tool/strip-rdoc.rb: ditto
* tool/vcs.rb: ditto
* tool/vtlh.rb: ditto
* tool/ytab.sed: ditto
* tool/enc-unicode.rb: fix typo
* tool/mk_call_iseq_optimized.rb: ditto
* tool/update-deps: ditto
  [ruby-core:76215] [Bug #12539]
  by Noah Gibbs <the.codefolio.guy@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55564 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/id2token.rb

@@ -1,5 +1,8 @@
 #! /usr/bin/ruby -p
 # -*- coding: us-ascii -*-
+
+# Used to build the Ruby parsing code in common.mk and Ripper.
+
 BEGIN {
   require 'optparse'
   $:.unshift(File.dirname(__FILE__))