Migrate provider documentation to tfplugindocs auto-generation

[maksym-nazarenko]

In order to use tfplugindocs to generate provider docs, all resources must have description field and exmaple/import file.

This issue will track all available resources and transition progress. Once all of them are done, //go:generate... directive will be introduced to close this issue.

• [x] provider (GH-83)
• [x] mikrotik_bgp_instance (GH-84)
• [x] mikrotik_bgp_peer (GH-85)
• [x] mikrotik_dhcp_lease (GH-86)
• [x] mikrotik_dhcp_server_network (GH-81)
• [x] mikrotik_dns_record (GH-87)
• [x] mikrotik_ip_address (GH-88)
• [x] mikrotik_ipv6_address (GH-89)
• [x] mikrotik_pool (GH-90)
• [x] mikrotik_scheduler (GH-91)
• [x] mikrotik_script (GH-92)
• [x] introduce new make goal docs to trigger go generate and build documentation (GH-104)

[maksym-nazarenko]

@ddelnano all pending PRs were rebased. Please, take a look when you have time

[ddelnano]

All the PRs are merged, so I think this is complete 🎉. Please close if you agree and really appreciate your work to standardize on the official documentation tool!

[maksym-nazarenko]

All the preparation work is done to actually do an auto generation in CI (will be a separate task) thank you @ddelnano for quick reviews and suggestions 👍