feat(core): Add slash command "related ticket" for ticket and ticket comments

ref: #284 closes #287

docs/projects/centurion_erp/user/core/tickets.md

@@ -47,12 +47,13 @@ Comment types are:
 
 Slash commands are a quick action that is specified after a slash command. As the name implies, the command starts with a slash `/`. The following slash commands are available:
 
+- Related `/blocked_by`, `/blocks` and `/relate`
+
 - Time Spent `/spend`, `/spent`
 
 
 ### Time Spent
 
-
 ::: app.core.lib.slash_commands.Duration
     options:
         inherited_members: false
@@ -62,6 +63,17 @@ Slash commands are a quick action that is specified after a slash command. As th
         summary: true
 
 
+### Related Tickets
+
+::: app.core.lib.slash_commands.CommandRelatedTicket
+    options:
+        inherited_members: false
+        members: []
+        show_bases: false
+        show_submodules: false
+        summary: true
+
+
 ## Ticket Types
 
 ::: app.core.models.ticket.ticket.Ticket.TicketType