Add .irbc and Rakefile to matching ruby filenames (#3457)

lib/linguist/languages.yml

@@ -3759,7 +3759,6 @@ Ruby:
   - ".fcgi"
   - ".gemspec"
   - ".god"
-  - ".irbrc"
   - ".jbuilder"
   - ".mspec"
   - ".pluginspec"
@@ -3781,6 +3780,7 @@ Ruby:
   - jruby
   - rbx
   filenames:
+  - ".irbrc"
   - ".pryrc"
   - Appraisals
   - Berksfile
@@ -3796,6 +3796,7 @@ Ruby:
   - Mavenfile
   - Podfile
   - Puppetfile
+  - Rakefile
   - Snapfile
   - Thorfile
   - Vagrantfile

samples/Ruby/filenames/.irbrc

@@ -0,0 +1,2 @@
+require "pp"
+IRB.conf[:AUTO_INDENT] = true