Revert "Change the indent space from 4 to 3 spaces."

This reverts commit f553de65de.

content/labs/infra/2019-04-14_how_to_use_Lego.md

@@ -21,28 +21,28 @@ SSL/TSL証明書を発行するにあたり、そのドメインの所有者が
 
 <div class="mermaid">
 sequenceDiagram
-   participant User
-   participant Web Server
-   participant Let’s Encrypt
-   participant DNS
+    participant User
+    participant Web Server
+    participant Let’s Encrypt
+    participant DNS
 
-   Note over User, DNS: 1. Resolve Host Name
-   User ->> DNS: Add A/CNAME record
+    Note over User, DNS: 1. Resolve Host Name
+    User ->> DNS: Add A/CNAME record
 
-   Note over User, DNS: 2. Start Listening (Port 80)
-   User ->> Web Server: Set up Web Server
+    Note over User, DNS: 2. Start Listening (Port 80)
+    User ->> Web Server: Set up Web Server
 
-   Note over User, DNS: 3. Request SSL/TSL Certificate
-   User ->> Let’s Encrypt: Request
-   Let’s Encrypt ->> User: File name
-   Let’s Encrypt ->> User: Token
-   User ->> Web Server: Put the file with the token
-   User ->> Let’s Encrypt: Request to continue
-   Let’s Encrypt ->> DNS: Name Resolution Request
-   DNS ->> Let’s Encrypt: Name Resolution Response
-   Let’s Encrypt ->> Web Server: HTTP Request (Port 80) via Internet
-   Web Server ->> Let’s Encrypt: HTTP Response (200) with the valid token
-   Let’s Encrypt ->> User: SSL/TSL Certificate
+    Note over User, DNS: 3. Request SSL/TSL Certificate
+    User ->> Let’s Encrypt: Request
+    Let’s Encrypt ->> User: File name
+    Let’s Encrypt ->> User: Token
+    User ->> Web Server: Put the file with the token
+    User ->> Let’s Encrypt: Request to continue
+    Let’s Encrypt ->> DNS: Name Resolution Request
+    DNS ->> Let’s Encrypt: Name Resolution Response
+    Let’s Encrypt ->> Web Server: HTTP Request (Port 80) via Internet
+    Web Server ->> Let’s Encrypt: HTTP Response (200) with the valid token
+    Let’s Encrypt ->> User: SSL/TSL Certificate
 </div>
 
 ### DNS-01認証