updated docs for Telegram bot (#39528)

source/_integrations/telegram_bot.markdown

@@ -41,8 +41,25 @@ This implementation allows Telegram to push updates directly to your server and
 
 Create your Telegram bot and [retrieve the API key](/integrations/telegram). The `api_key` will be used for adding the bot to Home Assistant during integration setup.
 
+### Allow Telegram bot to access your Home Assistant files (Optional)
+
+To enable Telegram bot to send local files, you must grant access to it by adding the file's folder to [`allowlist_external_dirs`](/integrations/homeassistant/#allowlist_external_dirs).
+
+Example `configuration.yaml`:
+
+```yaml
+homeassistant:
+  allowlist_external_dirs:
+    - "/media"
+```
+
 ### Allow Telegram to connect to your Home Assistant (Webhooks platform only)
 
+{% note %}
+This integration currently does not support self-signed certificates for HTTPS.
+If you are using the *Reverse proxy* or *Direct* method, please ensure that your certificates are signed by a public Certificate Authority (CA).
+{% endnote %}
+
 If you plan to use the `Webhooks` platform, you will need to allow Telegram to connect to your Home Assistant using one of the following methods:
 
 #### Home Assistant Cloud
@@ -58,6 +75,15 @@ If your Home Assistant is behind a publicly accessible reverse proxy (for exampl
    - Set `use_x_forwarded_for` to `true`.
    - Add the IP address of the reverse proxy to `trusted_proxies`.
 
+Example `configuration.yaml`:
+
+```yaml
+http:
+  use_x_forwarded_for: true
+  trusted_proxies:
+    - 192.168.0.0/16
+```
+
 #### Direct
 
 If your Home Assistant is publicly accessible, do the following:
@@ -87,7 +113,7 @@ If you have selected the `Webhooks` Telegram bot type, the integration setup wil
 URL:
   description: Allow to overwrite the external URL from the Home Assistant [configuration](/integrations/homeassistant/#editing-the-general-settings-in-yaml) for different setups (`https://<public_url>:<port>`).
 Trusted networks:
-  description: Telegram server access ACL as list.
+  description: Telegram server access ACL as list. Default is `149.154.160.0/20, 91.108.4.0/22`.
 {% endconfiguration_basic %}
 
 {% include integrations/option_flow.md %}
@@ -96,7 +122,7 @@ The integration can be configured to use a default parse mode for messages.
 
 {% configuration_basic %}
 Parse mode:
-  description: Default parser for messages if not explicit in message data, either `markdown` (legacy), `markdownv2` or `html`. Refer to Telegram's [formatting options](https://core.telegram.org/bots/api#formatting-options) for more information.
+  description: Default parser for messages if not explicit in message data, either `markdown` (legacy), `markdownv2`, `html` or `plain_text`. Refer to Telegram's [formatting options](https://core.telegram.org/bots/api#formatting-options) for more information.
 {% endconfiguration_basic %}
 
 ## Allowlisting chat IDs via Subentries