chore: Cleanup sponsors dead links (#6791)

The README and docs/index still contain companies that do not
contribute in their mentioned form (people moved on, company
stopped, ...).

This still gives them credit while removing dead links.

Signed-off-by: Jean-Philippe Evrard <jean-philippe.evrard+rochepub@external.roche.com>

README.md

@@ -60,18 +60,20 @@ Please create a PR and add your company or project to our [ADOPTERS.md file](ADO
 
 You can find the roadmap in our documentation: https://external-secrets.io/latest/contributing/roadmap/
 
-## Kicked off by
-
-![](assets/Godaddylogo_2020.png)
-
 ## Sponsored by
 
 ![Roche](assets/Roche_logo_blue_200px.png)
-![External Secrets Inc.](assets/ESI_Logo.svg)
 ![Container Solutions](assets/CS_logo_1.png)
 ![Form 3](assets/form3_logo.png)
-![Pento ](assets/pento_logo.png)
 
+## Special Thanks
+
+This project was kicked off by ![GoDaddy](assets/Godaddylogo_2020.png)
+
+It was also maintained and developed by the following companies:
+
+![External Secrets inc.](./pictures/ESI_Logo.svg)
+![Pento](./pictures/pento_logo.png)
 
 ## License
 [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2Fexternal-secrets%2Fexternal-secrets.svg?type=large)](https://app.fossa.com/projects/git%2Bgithub.com%2Fexternal-secrets%2Fexternal-secrets?ref=badge_large)

docs/index.md

@@ -2,9 +2,7 @@
 
 [![Roche](./pictures/Roche_logo_blue_200px.png)](https://www.roche.com/)
 [![cs-logo](./pictures/cs_logo.png)](https://container-solutions.com)
-[![External Secrets inc.](./pictures/ESI_Logo.svg)](https://externalsecrets.com)
 [![Form3](./pictures/form3_logo.png)](https://www.form3.tech/)
-[![Pento](./pictures/pento_logo.png)](https://www.pento.io)
 
 # Introduction
 
@@ -54,7 +52,13 @@ How to get involved:
 - [Contributing Process](contributing/process.md)
 - [Twitter](https://twitter.com/ExtSecretsOptr)
 
-### Kicked off by
+### Special thanks
+
+This project was kicked off by
 
 ![godaddy-logo](./pictures/godaddy_logo.png)
 
+It was also maintained and developed by the following companies:
+
+![External Secrets inc.](./pictures/ESI_Logo.svg)
+![Pento](./pictures/pento_logo.png)