Properly format indented code blocks

If a code block (surrounded by triple backticks) are indented, in other
words the code block is placed inside ordered or unordered list, the
closing backticks of codeblock should honor the original indentation
properly.

Signed-off-by: Khosrow Moossavi <khos2ow@gmail.com>

internal/template/sanitizer.go

@@ -55,7 +55,16 @@ func sanitizeSection(s string, settings *print.Settings) string {
 			if !strings.HasSuffix(segment, "\n") {
 				lastbreak = "\n"
 			}
-			segment = fmt.Sprintf("```%s%s```", segment, lastbreak)
+
+			// Adjust indention and linebreak for indented codeblock
+			// https://github.com/terraform-docs/terraform-docs/issues/521
+			lastindent := ""
+			lines := strings.Split(segment, "\n")
+			if len(strings.TrimSpace(lines[len(lines)-1])) == 0 {
+				lastbreak = ""
+			}
+
+			segment = fmt.Sprintf("```%s%s%s```", segment, lastindent, lastbreak)
 			return segment
 		},
 	)

internal/template/testdata/section/complex.expected

@@ -28,6 +28,16 @@ module "foo_bar" {
 }
 ```
 
+1. Entry one with code
+
+    ```json
+    {
+      "key": "value"
+    }
+    ```
+
+1. This line should not be broken
+
 Here is some trailing text after code block,
 followed by another line of text.
 

internal/template/testdata/section/complex.golden

@@ -28,6 +28,16 @@ module "foo_bar" {
 }
 ```
 
+1. Entry one with code
+
+    ```json
+    {
+      "key": "value"
+    }
+    ```
+
+1. This line should not be broken
+
 Here is some trailing text after code block,
 followed by another line of text.