Add ruby-openai gem by default, reverse order of instructions

Author: andreibondarev

lib/langchainrb_rails/generators/langchainrb_rails/pgvector_generator.rb

@@ -32,13 +32,14 @@ def add_to_model
       def add_to_gemfile
         # Dependency for Langchain PgVector
         gem "neighbor"
+        gem "ruby-openai"
       end
 
       def post_install_message
         say "Please do the following to start Q&A with your #{model_name} records:", :green
         say "1. Run `bundle install` to install the new gems."
-        say "2. Run `rails db:migrate` to apply the database migrations to enable pgvector and add the embedding column."
-        say "3. Set the env var OPENAI_API_KEY to your OpenAI API key."
+        say "2. Set `OPENAI_API_KEY` environment variable to your OpenAI API key."
+        say "3. Run `rails db:migrate` to apply the database migrations to enable pgvector and add the embedding column."
         say "4. In Rails console, run `#{model_name}.embed!` to set the embeddings for all records."
         say "5. Ask a question in the Rails console, ie: `#{model_name}.ask('[YOUR QUESTION]')`"
       end