fix(terraform_docs): Always use GNU sed

Ensure sed commands are compatible with MacOS and Linux/GNO version

Author: cschroer

README.md

@@ -585,8 +585,8 @@ Unlike most other hooks, this hook triggers once if there are any changed files
       To migrate everything 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'
+      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

hooks/terraform_docs.sh

@@ -40,8 +40,8 @@ function main {
 function replace_old_markers {
   local -r file=$1
 
-  sed -i "s/^${old_insertion_marker_begin}$/${insertion_marker_begin}/" "$file"
-  sed -i "s/^${old_insertion_marker_end}$/${insertion_marker_end}/" "$file"
+  sed -i'' "s/^${old_insertion_marker_begin}$/${insertion_marker_begin}/" "$file"
+  sed -i''  "s/^${old_insertion_marker_end}$/${insertion_marker_end}/" "$file"
 }
 
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