[DOCS] Adds initial content to Transforms readme.md (#80630) (#80687)

Co-authored-by: Walter Rafelsberger <[email protected]>
Co-authored-by: Pete Harverson <[email protected]>

Author: 3 people

docs/developer/plugin-list.asciidoc

@@ -499,8 +499,8 @@ routes, etc.
 |Gathers all usage collection, retrieving them from both: OSS and X-Pack plugins.
 
 
-|{kib-repo}blob/{branch}/x-pack/plugins/transform[transform]
-|WARNING: Missing README.
+|{kib-repo}blob/{branch}/x-pack/plugins/transform/readme.md[transform]
+|This plugin provides access to the transforms features provided by Elastic.
 
 
 |{kib-repo}blob/{branch}/x-pack/plugins/translations[translations]

x-pack/plugins/transform/readme.md

@@ -0,0 +1,117 @@
+# Documentation for Transforms UI developers
+
+This plugin provides access to the transforms features provided by Elastic.
+
+## Requirements
+
+To use the transforms feature, you must have at least a Basic license. For more 
+info, refer to 
+[Set up transforms](https://www.elastic.co/guide/en/elasticsearch/reference/current/transform-setup.html).
+
+
+## Setup local environment
+
+### Kibana
+
+1. Fork and clone the [Kibana repo](https://github.com/elastic/kibana).
+
+1. Install `nvm`, `node`, `yarn` (for example, by using Homebrew). See 
+   [Install dependencies](https://www.elastic.co/guide/en/kibana/master/development-getting-started.html#_install_dependencies).
+
+1. Make sure that Elasticsearch is deployed and running on `localhost:9200`.
+
+1. Navigate to the directory of the `kibana` repository on your machine.
+
+1. Fetch the latest changes from the repository.
+
+1. Checkout the branch of the version you want to use. For example, if you want 
+   to use a 7.9 version, run `git checkout 7.9`. (Your Elasticsearch and Kibana 
+   instances need to be the same version.)
+
+1. Run `nvm use`. The response shows the Node version that the environment uses. 
+   If you need to update your Node version, the response message contains the 
+   command you need to run to do it.
+
+1. Run `yarn kbn bootstrap`. It takes all the dependencies in the code and 
+   installs/checks them. It is recommended to use it every time when you switch 
+   between branches.
+
+1. Make a copy of `kibana.yml` and save as `kibana.dev.yml`. (Git will not track
+   the changes in `kibana.dev.yml` but yarn will use it.)
+   
+1. Provide the appropriate password and user name in `kibana.dev.yml`.
+
+1. Run `yarn start` to start Kibana.
+
+1. Go to http://localhost:560x/xxx (check the terminal message for the exact 
+   path).
+
+For more details, refer to this [getting started](https://www.elastic.co/guide/en/kibana/master/development-getting-started.html) page.
+
+### Adding sample data to Kibana
+
+Kibana has sample data sets that you can add to your setup so that you can test 
+different configurations on sample data.
+
+1. Click the Elastic logo in the upper left hand corner of your browser to 
+   navigate to the Kibana home page.
+
+1. Click *Load a data set and a Kibana dashboard*.
+
+1. Pick a data set or feel free to click *Add* on all of the available sample 
+   data sets.
+
+These data sets are now ready to be used for creating transforms in Kibana.
+
+## Running tests
+
+### Jest tests
+
+Run the test following jest tests from `kibana/x-pack`.
+
+New snapshots, all plugins:   
+
+```
+node scripts/jest
+```
+ 
+Update snapshots for the transform plugin: 
+
+```
+node scripts/jest plugins/transform -u
+```
+
+Update snapshots for a specific directory only: 
+
+```
+node scripts/jest x-pack/plugins/transform/public/app/sections
+```
+
+Run tests with verbose output: 
+
+```
+node scripts/jest plugins/transform --verbose
+```
+
+### Functional tests
+
+Before running the test server, make sure to quit all other instances of 
+Elasticsearch.
+
+1. From one terminal, in the x-pack directory, run:
+
+        node scripts/functional_tests_server.js --config test/functional/config.js
+
+   This command starts an Elasticsearch and Kibana instance that the tests will be run against.
+
+1. In another tab, run the following command to perform API integration tests (from the x-pack directory):
+
+        node scripts/functional_test_runner.js --include-tag transform --config test/api_integration/config
+        
+   The transform API integration tests are located in `x-pack/test/api_integration/apis/transform`.
+
+1. In another tab, run the following command to perform UI functional tests (from the x-pack directory):
+
+        node scripts/functional_test_runner.js --include-tag transform
+        
+   The transform functional tests are located in `x-pack/test/functional/apps/transform`.