Apply suggestions from code review

Co-authored-by: George L. Yermulnik <[email protected]>

hooks/terraform_docs.sh

@@ -264,11 +264,11 @@ function terraform_docs {
       #? TF 0.12+ and terraform-docs 0.12.0+
 
       #
-      # If `--add-to-existing-file=false` (default behavior), check is in file exist "hook markers",
-      # and if not skip execution to avoid addition of terraform-docs section -
-      # terraform-docs in 'inject' mode adds markers by default if they not present
+      # If `--add-to-existing-file=false` (default behavior), check if "hook markers" exist in file,
+      # and, if not, skip execution to avoid addition of terraform-docs section, as
+      # terraform-docs in 'inject' mode adds markers by default if they are not present
       #
-      if ! $add_to_existing; then
+      if [[ $add_to_existing == false ]]; then
         HAVE_MARKER=$(grep -o "$insertion_marker_begin" "$output_file" || exit 0)
         [[ ! $HAVE_MARKER ]] && continue
       fi
@@ -278,18 +278,18 @@ function terraform_docs {
     else
       #? TF 0.12+ and terraform-docs < 0.8
       #? Yes, we don't cover case of TF 0.12+ and terraform-docs 0.8-0.11
-      #? but I portably just drop this section in next release of the hook,
-      #? as there no sense to support hacks for tool versions which was released more than 3 years ago
+      #? but I probably just drop this section in next release of the hook,
+      #? as there's no sense to support hacks for tool versions which were released more than 3 years ago
 
       #
-      # If `--add-to-existing-file=true` set, check is in file exist "hook markers",
-      # and if not - append "hook markers" to the end of file.
+      # If `--add-to-existing-file=true` set, check if "hook markers" exist in file,
+      # and, if not, append "hook markers" to the end of the file.
       #
-      if $add_to_existing; then
+      if [[ $add_to_existing == true ]]; then
         HAVE_MARKER=$(grep -o "$insertion_marker_begin" "$output_file" || exit 0)
 
-        if [ ! "$HAVE_MARKER" ]; then
-          # Use of insertion markers, where addToExisting=true, with no markers in the existing file
+        if [[ ! $HAVE_MARKER ]]; then
+          # Use of insertion markers, when "add_to_existing=true" with no markers in the existing file
           echo "$insertion_marker_begin" >> "$output_file"
           echo "$insertion_marker_end" >> "$output_file"
         fi