Adopt welcome bot (#269)

Author: tkoyama010

.github/config.yml

@@ -0,0 +1,21 @@
+# Configuration for welcome - https://github.com/behaviorbot/welcome
+
+# Configuration for new-issue-welcome - https://github.com/behaviorbot/new-issue-welcome
+
+# Comment to be posted to on first time issues
+newIssueWelcomeComment: >
+  Thanks for opening your first issue here! Be sure to follow the issue template!
+
+# Configuration for new-pr-welcome - https://github.com/behaviorbot/new-pr-welcome
+
+# Comment to be posted to on PRs from first time contributors in your repository
+newPRWelcomeComment: >
+  Thanks for opening this pull request! Please check out our contributing guidelines.
+
+# Configuration for first-pr-merge - https://github.com/behaviorbot/first-pr-merge
+
+# Comment to be posted to on pull requests merged by a first time user
+firstPRMergeComment: >
+  Congrats on merging your first pull request! We here at behaviorbot are proud of you!
+
+# It is recommended to include as many gifs and emojis as possible!