Update Resources drop down menu to include 6 current customer case studies

[EstuaryRob]

Description

Need to reduce customer case study lines to maximize the number listed.

Work required

Format should be as follows: Customer name 1-line description (with link) Thumbnail centered to the left

Updated text is here: https://docs.google.com/document/d/1skS66dG4Tn2GTd9A0KcUEYF6yu6C_dy1qsTtBMHLJ3M/edit?usp=sharing

• [ ] engineering will fill this in

Figma / Designs

include any screenshots/links of designs

[travjenkins]

https://github.com/estuary/marketing-site/issues/360 will handle this