### Description

Backport of the description-block portion of master commit [3ee29a3](https://github.com/odoo/odoo/commit/3ee29a3dbbdf7a3504ef84e839f57fa63321d93e) ("[IMP] base, mail: better docutils warnings, fix mail description") to the 19.0 stable branch.

On 19.0, the `mail` manifest description still emits these docutils warnings:

```
<manifest description>:38: (ERROR/3) Unexpected indentation.
<manifest description>:43: (WARNING/2) Block quote ends without a blank line; unexpected unindent.
```

caused by a 4-space indented bullet list immediately following an unrelated underlined heading, with no blank lines around it.

### Fix

Drop the spurious heading underline, de-indent the bullets, and add the required blank lines around the list - matching exactly what is already on master.

### Diff (only the description block changes)

```diff
 This can be used to easily create email-based workflows for many email-enabled Odoo documents, such as:
-----------------------------------------------------------------------------------------------------------
-    * CRM Leads/Opportunities
-    * CRM Claims
-    * Project Issues
-    * Project Tasks
-    * Human Resource Recruitment (Applicants)
+
+* CRM Leads/Opportunities
+* CRM Claims
+* Project Issues
+* Project Tasks
+* Human Resource Recruitment (Applicants)
+
 Just install the relevant application, and you can assign any of these document
```

### Notes

- No functional change; only the rendered description is affected.
- Verified locally with docutils that the description now parses cleanly.
- Master already has this fix via 3ee29a3.