Fix unrendered "example" section

[Rindrics]

Chores

• execute tfplugindocs migrate to let preexistent "Example Usage" section being recognized by registry website

Before/After applying this PR

Before

"Example Usage" section is not shown on site although it exists in the code:
https://registry.terraform.io/providers/SigNoz/signoz/0.0.4/docs/resources/alert

After

"Example Usage" section is recognized and shown on site:
https://registry.terraform.io/providers/Rindrics/signoz/0.0.1/docs/resources/alert

Note

• I wanted to delete & ignore docs/*, but left it as it is because we cannot dynamically include them to the releases
  • because .Name and .Path template variable is paid-feature of goreleaser

[grandwizard28]

Thank you for your contribution @Rindrics

[Rindrics]

thanks, I converted this PR to draft because I found something to check.

[Rindrics]

I surveyed whether we can remove & ignore docs/ but finally found we cannot.

• I wrote to the description what I found during the survey : Fix unrendered "example" section #23 (comment)

[Rindrics]

would you take a look at this PR? @grandwizard28