Init @kbn/es readme (#39850)

* init kbn-es readme

* formatting

packages/kbn-es/README.md

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+# @kbn/es
+
+> A command line utility for running elasticsearch from source or archive.
+
+## Getting started
+If running elasticsearch from source, elasticsearch needs to be cloned to a sibling directory of Kibana.
+
+To run, go to the Kibana root and run `node scripts/es --help` to get the latest command line options.
+
+### Examples
+
+Run a snapshot install with a trial license
+```
+node scripts/es snapshot --license=trial
+```
+
+Run from source with a configured data directory
+```
+node scripts/es source --Epath.data=/home/me/es_data
+```
+
+## API
+
+### run
+Start a cluster
+```
+var es = require('@kbn/es');
+es.run({
+  license: 'basic',
+  version: 7.0,
+})
+.catch(function (e) {
+  console.error(e);
+  process.exitCode = 1;
+});
+```
+
+#### Options
+
+##### options.license
+
+Type: `String`
+
+License type, one of: trial, basic, gold, platinum
+
+##### options.version
+
+Type: `String`
+
+Desired elasticsearch version
+
+##### options['source-path']
+
+Type: `String`
+
+Cloned location of elasticsearch repository, used when running from source
+
+##### options['base-path']
+
+Type: `String`
+
+Location where snapshots are cached