docs: fix custom container syntax

docs/backups.md

@@ -296,9 +296,8 @@ When it's done exporting, we'll remove the snapshot. Note: this operation will t
 Concurrency is a parameter that let you define how many VMs your backup job will manage simultaneously.
 
 :::tip
-
 - Default concurrency value is 2 if left empty.
-  :::
+:::
 
 Let's say you want to backup 50 VMs (each with 1x disk) at 3:00 AM. There are **2 different strategies**:
 

docs/installation.md

@@ -18,10 +18,9 @@ Once you have started the VM, you can access the web UI by putting the IP you co
 - Check your router's DHCP leases for an `xoa` lease
 
 :::tip
-
 - Default Web UI credentials are `admin@admin.net` / `admin`
 - Default console/SSH credentials are not set, you need to set them [as described here](troubleshooting.md#set-or-recover-xoa-vm-password).
-  :::
+:::
 
 ### Registration
 

docs/manage_infrastructure.md

@@ -544,10 +544,9 @@ As specified in the [documentation](https://xcp-ng.org/docs/requirements.html#po
 :::
 
 :::warning
-
 - Even with matching CPU vendors, in the case of different CPU models, XCP-ng/Citrix Hypervisor will "level" down to use the CPU having the least instructions.
 - All the hosts in a pool must run the same XCP-ng version.
-  :::
+:::
 
 ### Creating a pool
 

docs/purchase.md

@@ -40,10 +40,9 @@ The second step is to select your purchase option:
 - Paid period: **check or wire transfer only**. This purchase allows you to subscribe for a one, two or three year period
 
 :::tip
-
 - A 2 year subscription period grants you 1 month discounted
 - A 3 year subscription period grants you 2 months discounted
-  :::
+:::
 
 Then you need to fill in your information and select **"Buy for my own use"** (direct purchase)
 

docs/sdn_controller.md

@@ -35,11 +35,10 @@ In the network creation view:
 ![](./assets/sdn-controller.png)
 
 :::tip
-
 - All hosts in a private network must be able to reach the other hosts' management interface and all hosts must be able to reach one another on the interface selected for private networks creation.
   > The term ‘management interface’ is used to indicate the IP-enabled NIC that carries the management traffic.
 - Only 1 encrypted GRE network and 1 encrypted VxLAN network per pool can exist at a time due to Open vSwitch limitation.
-  :::
+:::
 
 ### Configuration
 
@@ -94,9 +93,8 @@ In the VM network tab a new column has been added: _Network rules_.
 ![](./assets/show-rules.png)
 
 :::tip
-
 - This feature requires the OpenFlow port (TCP 6653) to be opened. (See [the requirements](#openflow))
-  :::
+:::
 
 ### Requirements