Added DevOpsDays Atlanta 2023 (#575)

* Added DevOpsDays Atlanta

* Update README.md

---------

Co-authored-by: Aurelie Vache <[email protected]>

README.md

@@ -80,6 +80,7 @@ All the data (past and coming) is available publicly in JSON:
 * 14-17: [EuroBSDCon](https://2023.eurobsdcon.org/) - Coimbra (Portugal) <a href="https://2023.eurobsdcon.org/call-for-papers-is-now-open/"><img alt="CFP EuroBSDCon" src="https://img.shields.io/static/v1?label=CFP&message=until%2026-May-2023&color=red"></a>
 * 18: [Agile Tour Montpellier](https://agiletourmontpellier.fr/) - Montpellier (France) <a href="https://conference-hall.io/public/event/mXxbggAyDUbTFXazxkWX"><img alt="CFP Agile Tour Montpellier" src="https://img.shields.io/static/v1?label=CFP&message=until%2015-June-2023&color=red"></a>
 * 18-19: [Shift Conference](https://shift.infobip.com) - Zadar (Croatia) <a href="https://sessionize.com/infobip-shift-2023/"><img alt="CFP Infobip Shift" src="https://img.shields.io/static/v1?label=CFP&message=until%2015-May-2023&color=red"></a>
+* 18-19: [DevOpsDays Atlanta](https://devopsdays.org/events/2023-atlanta/welcome/) - Atlanta, GA (USA) <a href="https://www.papercall.io/devopsdaysatl2023"><img alt="CFP DevOpsDays Atlanta" src="https://img.shields.io/static/v1?label=CFP&message=until%2010-July-2023&color=red"></a>
 * 18-21: [NDC TechTown](https://ndctechtown.com/) - Kongsberg (Norway) <a href="https://ndctechtown.com/call-for-papers"><img alt="CFP NCD TechTown" src="https://img.shields.io/static/v1?label=CFP&message=until%2019-May-2023&color=red"></a>
 * 19-20: [Agile en Seine](https://www.agileenseine.com/) - Paris (France) <a href="https://sessionize.com/agile-en-seine-2023/"><img alt="CFP Agile en Seine" src="https://img.shields.io/static/v1?label=CFP&message=until%2018-June-2023&color=red"></a>
 * 19-21: [The Linux Foundation Open Source Summit Europe](https://events.linuxfoundation.org/open-source-summit-europe/) - Bilbao (Spain) & Online