Update project page text, remove Drupal 7 modules

Problem/Motivation

Drupal 7 is EOL, but some modules are mentioned at the top, with only Drupal 7 releases.

Steps to reproduce

Proposed resolution

Update the project page text to this?

Compatibility

This module is compatible with Search API → and Search API Solr → . Is not tested with Apache Solr Integration module.

Also, maybe remove the "Drupal 8" section?

Remaining tasks

User interface changes

API changes

Data model changes