add dev gem to generate erd

Gemfile.lock

@@ -90,6 +90,7 @@ GEM
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
     childprocess (3.0.0)
+    choice (0.2.0)
     coderay (1.1.3)
     concurrent-ruby (1.1.8)
     connection_pool (2.2.5)
@@ -223,6 +224,11 @@ GEM
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
+    rails-erd (1.6.1)
+      activerecord (>= 4.2)
+      activesupport (>= 4.2)
+      choice (~> 0.2.0)
+      ruby-graphviz (~> 1.2)
     rails-html-sanitizer (1.3.0)
       loofah (~> 2.3)
     rails-i18n (6.0.0)
@@ -285,6 +291,8 @@ GEM
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 0.90.0, < 2.0)
+    ruby-graphviz (1.2.5)
+      rexml
     ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.4)
     rubyzip (2.3.0)
@@ -403,6 +411,7 @@ DEPENDENCIES
   puma (~> 5.0)
   rack-mini-profiler (~> 2.0)
   rails (~> 6.1.3, >= 6.1.3.1)
+  rails-erd
   rails-i18n (~> 6.0.0)
   rbattlenet (~> 2.2.4)!
   redis (~> 4.2.5)