Fix collapsed markdown for enum values on Terraform website

[nownabe]

Release Note Template for Downstream PRs (will be copied)

Fix markdown for enum values

I fixed a collapsed markdown for enum values on the Terraform website.

Current docs are like the following:

https://www.terraform.io/docs/providers/google/r/dns_managed_zone.html#visibility

Sample diff made by this PR:

diff --git a/website/docs/r/app_engine_domain_mapping.html.markdown b/website/docs/r/app_engine_domain_mapping.html.markdown
index 14b8bad2..4146a26a 100644
--- a/website/docs/r/app_engine_domain_mapping.html.markdown
+++ b/website/docs/r/app_engine_domain_mapping.html.markdown
@@ -64,18 +64,15 @@ The following arguments are supported:
 
 * `ssl_settings` -
   (Optional)
-  SSL configuration for this domain. If unconfigured, this domain will not serve with SSL.  Structure is documented below.
+  SSL configuration for this domain. If unconfigured, this domain will not serve with SSL.
+  Structure is documented below.
 
 * `override_strategy` -
   (Optional)
   Whether the domain creation should override any existing mappings for this domain.
   By default, overrides are rejected.
-
-  Default value: `STRICT`
-
-  Possible values are:
-  * `STRICT`
-  * `OVERRIDE`
+  Default value is `STRICT`.
+  Possible values are `STRICT` and `OVERRIDE`.
 
 * `project` - (Optional) The ID of the project in which the resource belongs.
     If it is not provided, the provider project is used.

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

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@ndmckinley, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 109 files changed, 1249 insertions(+), 1636 deletions(-))
Terraform Beta: Diff ( 130 files changed, 1485 insertions(+), 1927 deletions(-))

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=135668"

[nat-henderson]

Thank you, the diff looks great.