Update docs/hooks/hook_civicrm_alterMailContent.md

Co-Authored-By: Mikey O'Toole <mikey@mjco.uk>

docs/hooks/hook_civicrm_alterMailContent.md

@@ -19,7 +19,7 @@ $content - fields include: html, text, subject, groupName, valueName, messageTem
 Note that this hook is fired when: 
 
 * creating mailings through the traditional BAO mailer (standard CiviMail)
-- creating mailings through FlexMailer (used by Mosaico)
+* creating mailings through FlexMailer (used by Mosaico)
 - sending emails using message templates, in CRM_Core_BAO_MessageTemplate
 
 In the latter case there is inherently no mailingID, so this will not be supplied. Similarly in the 2 former cases the messageTemplateID is not supplied.