Bump github.com/hashicorp/terraform-plugin-docs from 0.7.0 to 0.13.0

Bumps [github.com/hashicorp/terraform-plugin-docs](https://github.com/hashicorp/terraform-plugin-docs) from 0.7.0 to 0.13.0.
- [Release notes](https://github.com/hashicorp/terraform-plugin-docs/releases)
- [Changelog](https://github.com/hashicorp/terraform-plugin-docs/blob/main/CHANGELOG.md)
- [Commits](https://github.com/hashicorp/terraform-plugin-docs/compare/v0.7.0...v0.13.0)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/terraform-plugin-docs
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/github.com/Masterminds/sprig/v3/Makefile

@@ -0,0 +1,9 @@
+.PHONY: test
+test:
+	@echo "==> Running tests"
+	GO111MODULE=on go test -v
+
+.PHONY: test-cover
+test-cover:
+	@echo "==> Running Tests with coverage"
+	GO111MODULE=on go test -cover .