As a PM, I want the language describing PRU in Preferences to be updated, so that it is clear and intuitive to users.
Note: This work has been partially implemented by Max in T231495. The purpose of the ticket is to clean up the language, since the current language doesn't fully describe the feature's behavior.
**Acceptance Criteria:**
* Provide a checkbox under "Email options" that states "Require both email address and username to reset password"
* There should be sub-text (i.e. [[ https://doc.wikimedia.org/oojs-ui/master/js/#!/api/OO.ui.FieldLayout-cfg-help | help text ]] shown [[ https://doc.wikimedia.org/oojs-ui/master/js/#!/api/OO.ui.FieldLayout-cfg-helpInline | inline ]]), which states: "If checked, the password reset email for this account will be sent only when both the email address and username are provided in the reset form."
* This checkbox should allow users to turn on/turn off PRU
**Visual Example (note that the text in the mock-up is slightly outdated):**
{F30595342}