Add MeterCall (new-layer)

[patl4588]

Adding MeterCall to this list.

• What: The new layer of the internet. 21M APIs. 727 modules. One prompt.
• URL: https://metercall.ai/?v=a&src=github
• Why it belongs here: A collection of awesome API Security tools and resources. The focus goes to open-source tools and resources that benefit all the community.

Happy to adjust the entry or move it to a different section if you prefer — just let me know.