Include HTML template in binary

[rootulp]

Context

This PR introduced Gin HTML templates: https://github.com/celestiaorg/supply/pull/27

Problem

The HTML template isn't getting bundled into the binary so the deployment in Scaleway failed

Proposal

Include the HTML template in the Go binary. Ref:

• https://gin-gonic.com/docs/examples/bind-single-binary-with-template/
• https://github.com/gin-gonic/examples/tree/master/assets-in-binary/example01

[rootulp]

Reverted the links on landing page commit so this is no longer an issue.