Create manual_installation_production.md

I think it's this. Please review to be sure that I am not missing anything.
I was a bit confused with the directory links in the installer instructions, because in unix you don't create directories to then link them, since the command `ln -s` already creates the linked directory. But I think it's this. Please review and amend it accordingly

docs/SUMMARY.md

@@ -20,6 +20,7 @@
     * [Installer](en/installation/installer.md)
     * [Create a deploy user](en/installation/create_deploy_user.md)
     * [Generating SSH Key](en/installation/generating_ssh_key.md)
+    * [Manual installation (not recommended)](en/installation/manual_installation_production.md)
     * [Digital Ocean](en/installation/digital_ocean.md)
     * [Heroku](en/installation/deploying-on-heroku.md)
     * [Docker](en/installation/docker.md)

docs/en/installation/manual_installation_production.md

@@ -0,0 +1,94 @@
+# Manual installation for production
+
+**WARNING:** This method is *not recommended* and not officially supported, since you should use the [installer](https://github.com/consul/installer) instead. Use this method if the installer isn't an option and you can already deal with PostgreSQL, puma or passenger, NGNIX and SSL (with letsencrypt, for instance).
+
+This guide assumes you've already [installed all the necessary packages](prerequisites.md) on your system.
+
+The created directory structure herein is to be used with [capistrano](https://capistranorb.com/documentation/getting-started/structure/).
+
+## Folder structure
+
+First, create the main folder, clone the repo to a repo directory, and create the needed folders:
+
+```
+mkdir consul
+cd consul
+git clone --mirror https://github.com/consul/consul.git repo
+mkdir releases shared
+mkdir shared/log shared/tmp shared/config shared/public shared/storage
+mkdir -p shared/public/assets shared/public/system shared/public/ckeditor_assets shared/public/machine_learning/data
+```
+
+## Initial release
+
+Extract from the repo the first release to the respective directory, and create the symbolic link of the current release (replace `<latest_consul_stable_version>` with the latest version number, like 1.3.1 or 1.4.1):
+
+```
+cd repo
+git archive <latest_consul_stable_version> | tar -x -f - -C ../releases/first
+cd ..
+ln -s releases/first current
+```
+
+## Gems installation
+
+Install the gems CONSUL depends on:
+
+```
+cd releases/first
+bundle install --path ../../shared/bundle --without development test
+cd ../..
+```
+
+## Configuration files
+
+Generate the `database.yml` and `secrets.yml` files:
+
+```
+cp current/config/secrets.yml.example shared/config/secrets.yml
+cp current/config/database.yml.example shared/config/database.yml
+cd releases/first/config
+ln -s ../../../shared/config/database.yml
+ln -s ../../../shared/config/secrets.yml
+cd ../../..
+```
+
+Edit the `shared/config/database.yml` file, filling in `username` and `password` with the data generated during the [PostgreSQL setup](debian.md#postgresql-94).
+
+We now need to generate a secret key:
+
+```
+cd current
+bin/rake secret RAILS_ENV=production
+cd ..
+```
+
+Copy that generated key, and edit the `shared/config/secrets.yml` file; under the section `production`, change the following data:
+
+```
+  secret_key_base: enter_the_secret_key_you_have_just_generated
+  server_name: enter_your_domain
+```
+
+If you aren't using a SSL certificate, replace the line saying `force_ssl: true` with `force_ssl: false`.
+
+## Database setup
+
+Create a database, load the seeds and compile the assets:
+
+```
+ cd current
+ bin/rake db:migrate RAILS_ENV=production
+ bin/rake db:seed RAILS_ENV=production
+ bin/rake assets:precompile RAILS_ENV=production
+```
+
+## Starting the application
+
+And, finally, start the Rails server:
+
+```
+bin/rails s -e production
+```
+
+Congratulations! Your server is now running in the production environment :smile:.