added detailed commands information (#17)

Added commands as a detail every time the bot replies. This way we don't
need to call `help` and it can be minimized.

This resolves #15

It is shown in the following way:

---

Enabled `auto-merge` in Pull Request


<details><summary> <b>Available commands</b> </summary>


- `/merge`: Enables auto-merge for Pull Request
- `/merge cancel`: Cancels auto-merge for Pull Request
- `/merge help`: Shows this menu

For more information see the
[documentation](https://github.com/paritytech/auto-merge-bot)

</details>

src/bot.ts

@@ -9,15 +9,20 @@ const BOT_COMMAND = "/merge";
 type Command = "merge" | "cancel" | "help";
 
 const botCommands = `
-**Available commands**
-
 - \`/merge\`: Enables auto-merge for Pull Request
 - \`/merge cancel\`: Cancels auto-merge for Pull Request
 - \`/merge help\`: Shows this menu
 
 For more information see the [documentation](https://github.com/paritytech/auto-merge-bot)
 `;
 
+const detailCommands = `
+<details><summary> <b>Available commands</b> </summary>
+
+${botCommands}
+</details> 
+`;
+
 export class Bot {
   constructor(
     private readonly comment: IssueComment,
@@ -91,21 +96,21 @@ export class Bot {
           await this.commentsApi.reactToComment(this.comment.id, "+1");
           await merger.enableAutoMerge();
           await this.commentsApi.comment(
-            "Enabled `auto-merge` in Pull Request",
+            "Enabled `auto-merge` in Pull Request\n\n" + detailCommands,
           );
           break;
         // `/merge cancel`
         case "cancel":
           await this.commentsApi.reactToComment(this.comment.id, "+1");
           await merger.disableAutoMerge();
           await this.commentsApi.comment(
-            "Disabled `auto-merge` in Pull Request",
+            "Disabled `auto-merge` in Pull Request\n\n" + detailCommands,
           );
           break;
         // `/merge help`
         case "help":
           await this.commentsApi.comment(
-            "## Auto-Merge-Bot\n" + botCommands,
+            "## Auto-Merge-Bot\n\n" + "**Available commands**" + botCommands,
             true,
           );
           break;
@@ -115,7 +120,7 @@ export class Bot {
           await this.commentsApi.comment(
             "## Auto-Merge-Bot\n" +
               `Command \`${command}\` not recognized.\n\n` +
-              botCommands,
+              detailCommands,
             true,
           );
         }