HTML validation: Quote <my-bot> and <api_key> placeholders in api docs.

They were being sent to the browser as non-renderable HTML tags.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

templates/zerver/api/running-bots.md

@@ -77,7 +77,7 @@ Zulip Botserver.
 
 * My bot won't start
     * Ensure that your API config file is correct (download the config file from the server).
-    * Ensure that your bot script is located in zulip_bots/bots/<my-bot>/
+    * Ensure that your bot script is located in `zulip_bots/bots/<my-bot>/`
     * Are you using your own Zulip development server? Ensure that you run your bot outside
       the Vagrant environment.
     * Some bots require Python 3. Try switching to a Python 3 environment before running

templates/zerver/api/webhook-walkthrough.md

@@ -183,7 +183,7 @@ webhook, you have written enough code to test your integration.
 
 First, get an API key from the Your bots section of your Zulip user's Settings
 page. If you haven't created a bot already, you can do that there. Then copy
-its API key and replace the placeholder "<api_key>" in the examples with
+its API key and replace the placeholder `<api_key>` in the examples with
 your real key. This is how Zulip knows the request is from an authorized user.
 
 Now you can test using Zulip itself, or curl on the command line.

templates/zerver/api/writing-bots.md

@@ -498,7 +498,7 @@ to see examples of bot tests.
 
 * My bot won't start
     * Ensure that your API config file is correct (download the config file from the server).
-    * Ensure that you bot script is located in zulip_bots/bots/<my-bot>/
+    * Ensure that you bot script is located in `zulip_bots/bots/<my-bot>/`
     * Are you using your own Zulip development server? Ensure that you run your bot outside
       the Vagrant environment.
     * Some bots require Python 3. Try switching to a Python 3 environment before running