[docs] Migrate docs from AsciiDoc to Markdown (#2635)

* delete asciidoc files

* add migrated files

* Apply suggestions from review

Co-authored-by: Josh Mock <josh@joshmock.com>

* Apply suggestions from review

Co-authored-by: Josh Mock <josh@joshmock.com>

* add the new ci checks (#2634)

---------

Co-authored-by: Marci W <333176+marciw@users.noreply.github.com>
Co-authored-by: Josh Mock <josh@joshmock.com>

docs/reference/msearch_examples.md

@@ -0,0 +1,63 @@
+---
+mapped_pages:
+  - https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/msearch_examples.html
+---
+
+# MSearch [msearch_examples]
+
+The multi search API allows to execute several search requests within the same API.
+
+```js
+'use strict'
+
+const { Client } = require('@elastic/elasticsearch')
+const client = new Client({
+  cloud: { id: '<cloud-id>' },
+  auth: { apiKey: 'base64EncodedKey' }
+})
+
+async function run () {
+  const bulkResponse = await client.bulk({
+    refresh: true,
+    operations: [
+      { index: { _index: 'game-of-thrones' } },
+      {
+        character: 'Ned Stark',
+        quote: 'Winter is coming.'
+      },
+
+      { index: { _index: 'game-of-thrones' } },
+      {
+        character: 'Daenerys Targaryen',
+        quote: 'I am the blood of the dragon.'
+      },
+
+      { index: { _index: 'game-of-thrones' } },
+      {
+        character: 'Tyrion Lannister',
+        quote: 'A mind needs books like a sword needs a whetstone.'
+      }
+    ]
+  })
+
+  if (bulkResponse.errors) {
+    console.log(bulkResponse)
+    process.exit(1)
+  }
+
+  const result = await client.msearch({
+    searches: [
+      { index: 'game-of-thrones' },
+      { query: { match: { character: 'Daenerys' } } },
+
+      { index: 'game-of-thrones' },
+      { query: { match: { character: 'Tyrion' } } }
+    ]
+  })
+
+  console.log(result.responses)
+}
+
+run().catch(console.log)
+```
+