Inaccurate guidance about hosting on Vercel

[ArvinZJC]

Prerequisites

• I have searched for duplicate or closed feature requests
• I am mindful of the project scope

Proposal

When hosting on Vercel, overriding the install command, as guided in the docs, can lead to a timeout. Besides, a proper env variable may need to be set.

Motivation and context

• The install command should be dnf install -y golang or yum install -y golang.
• HUGO_VERSION env variable is needed. At the time of opening this issue, a proper setting would be like HUGO_VERSION=0.136.5. That is, set to a version the same as declared in hugoblox.yaml. Otherwise, Vercel may automatically select an ancient version of Hugo.