Add Akvelon to case-studies (apache#17611)

* add image and md file to case-studies

* change text solid for deep

website/www/site/content/en/case-studies/akvelon.md

@@ -0,0 +1,19 @@
+---
+title:  "Akvelon"
+icon: /images/logos/powered-by/akvelon.png
+hasNav: true
+cardDescription: "Akvelon is a software engineering company that helps start-ups, SMBs, and Fortune 500 companies unlock the full potential of cloud, data, and AI/ML to empower their strategic advantage. Akvelon team has deep expertise in integrating Apache Beam with diverse data processing ecosystems and is an enthusiastic Apache Beam community contributor."
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->