Add Update The Gmefile Bundled With Version as a Ruby til

ruby/update-the-gemfile-bundled-with-version.md

@@ -0,0 +1,29 @@
+# Update The Gemfile Bundled With Version
+
+When you run `bundle install`, whatever is the latest version of `bundler`
+installed locally will be used. Your `Gemfile` dependencies will be installed
+and the `Gemfile.lock` will be marked at the bottom with a signature for the
+version of `bundler` that was used.
+
+```ruby
+# Gemfile.lock
+...
+
+BUNDLED WITH
+   1.1.17
+```
+
+On future `bundle install` calls, a matching major version of Bundler will be
+used. If you'd like to migrate from 1.x.x to 2.x.x or vice versa, or even if
+you want to explicitly change minor versions, you can run:
+
+```bash
+$ bundle update --bundler=2.2.4
+```
+
+This will bundle your project with `2.2.4` and update the `BUNDLED WITH`
+section to reflect that.
+
+Use the version that makes sense for you with the `--bundler` flag.
+
+[source](https://bundler.io/guides/bundler_2_upgrade.html#upgrading-applications-from-bundler-1-to-bundler-2)