feat(terraform_docs): Add terraform-docs default markers support and describe how to migrate to them (#609)

---------

Co-authored-by: Jon M <arxro008@euro.ngc.com>
Co-authored-by: George L. Yermulnik <yz@yz.kiev.ua>
Co-authored-by: Maksym Vlasov <MaxymVlasov@users.noreply.github.com>

README.md

@@ -486,6 +486,13 @@ Unlike most other hooks, this hook triggers once if there are any changed files
     * create a documentation file
     * extend existing documentation file by appending markers to the end of the file (see item 1 above)
     * use different filename for the documentation (default is `README.md`)
+    * use the same insertion markers as `terraform-docs` by default. It will be default in `v2.0`.  
+      To migrate to `terraform-docs` insertion markers, run in repo root:
+
+      ```bash
+      grep -rl 'BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK' . | xargs sed -i 's/BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK/BEGIN_TF_DOCS/g'
+      grep -rl 'END OF PRE-COMMIT-TERRAFORM DOCS HOOK' . | xargs sed -i 's/END OF PRE-COMMIT-TERRAFORM DOCS HOOK/END_TF_DOCS/g'
+      ```
 
     ```yaml
     - id: terraform_docs
@@ -493,6 +500,7 @@ Unlike most other hooks, this hook triggers once if there are any changed files
         - --hook-config=--path-to-file=README.md        # Valid UNIX path. I.e. ../TFDOC.md or docs/README.md etc.
         - --hook-config=--add-to-existing-file=true     # Boolean. true or false
         - --hook-config=--create-file-if-not-exist=true # Boolean. true or false
+        - --hook-config=--use-standard-markers=true     # Boolean. Defaults in v1.x to false. Set to true for compatibility with terraform-docs
     ```
 
 4. You can provide [any configuration available in `terraform-docs`](https://terraform-docs.io/user-guide/configuration/) as an argument to `terraform_doc` hook, for example: