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.

• provider (prepare provider for tfplugindocs #83)
• mikrotik_bgp_instance (prepare mikrotik_bgp_instance resource for tfplugindocs #84)
• mikrotik_bgp_peer (Prepare mikrotik_bgp_peer for tfplugindocs #85)
• mikrotik_dhcp_lease (Docs/mikrotik dhcp lease #86)
• mikrotik_dhcp_server_network (Resource/dhcp server network #81)
• mikrotik_dns_record (Docs/mikrotik dns record #87)
• mikrotik_ip_address (Docs/mikrotik ip address #88)
• mikrotik_ipv6_address (Docs/mikrotik ipv6 address #89)
• mikrotik_pool (Docs/mikrotik pool #90)
• mikrotik_scheduler (Docs/mikrotik scheduler #91)
• mikrotik_script (Docs/mikrotik script #92)
• introduce new make goal docs to trigger go generate and build documentation (use go generate to generate provider docs #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 👍