Chore: Add Facebook app set up documentation (#647)

Co-authored-by: Pranav Raj S <pranavrajs@gmail.com>

.env.example

@@ -22,17 +22,6 @@ POSTGRES_PASSWORD=
 RAILS_ENV=development
 RAILS_MAX_THREADS=5
 
-#fb app
-FB_VERIFY_TOKEN=
-FB_APP_SECRET=
-FB_APP_ID=
-
-#twitter app
-TWITTER_APP_ID=
-TWITTER_CONSUMER_KEY=
-TWITTER_CONSUMER_SECRET=
-TWITTER_ENVIRONMENT=
-
 #mail
 MAILER_SENDER_EMAIL=accounts@chatwoot.com
 SMTP_PORT=1025
@@ -59,13 +48,25 @@ AWS_REGION=
 SENTRY_DSN=
 
 #Log settings
-LOG_LEVEL=
-LOG_SIZE= 
+LOG_LEVEL=info
+LOG_SIZE=500 
 
 # Credentials to access sidekiq dashboard in production
 SIDEKIQ_AUTH_USERNAME=
 SIDEKIQ_AUTH_PASSWORD=
 
+### This environment variables are only required if you are setting up social media channels
+#facebook 
+FB_VERIFY_TOKEN=
+FB_APP_SECRET=
+FB_APP_ID=
+
+#twitter
+TWITTER_APP_ID=
+TWITTER_CONSUMER_KEY=
+TWITTER_CONSUMER_SECRET=
+TWITTER_ENVIRONMENT=
+
 ####  This environment variables are only required in hosted version which has billing
 ENABLE_BILLING=