doc: Fixed notes formatting

Fixed the style used to format notes.

Signed-off-by: Francesco Servidio <francesco.servidio@nordicsemi.no>
diff --git a/docs/design.md b/docs/design.md
index 8d8e0fe..297308c 100755
--- a/docs/design.md
+++ b/docs/design.md
@@ -417,10 +417,15 @@
 The offset immediately following such a record represents the start of the next
 flash area.
 
-Note: "min-write-size" is a property of the flash hardware.  If the hardware
-allows individual bytes to be written at arbitrary addresses, then
-min-write-size is 1.  If the hardware only allows writes at even addresses,
-then min-write-size is 2, and so on.
+---
+***Note***
+
+*"min-write-size" is a property of the flash hardware.  If the hardware*
+*allows individual bytes to be written at arbitrary addresses, then*
+*min-write-size is 1.  If the hardware only allows writes at even addresses,*
+*then min-write-size is 2, and so on.*
+
+---
 
 An image trailer contains the following fields:
 
@@ -507,9 +512,14 @@
 image trailers.  It is better to map all the possible trailer states to the swap
 types described above via a set of tables.  These tables are reproduced below.
 
-Note: An important caveat about the tables described below is that they must
-be evaluated in the order presented here. Lower state numbers must have a
-higher priority when testing the image trailers.
+---
+***Note***
+
+*An important caveat about the tables described below is that they must*
+*be evaluated in the order presented here. Lower state numbers must have a*
+*higher priority when testing the image trailers.*
+
+---
 
 ```
     State I
@@ -571,11 +581,16 @@
 result is either `BOOT_SWAP_TYPE_FAIL` or `BOOT_SWAP_TYPE_PANIC`, MCUboot hangs
 rather than booting an invalid or compromised image.
 
-Note: An important caveat to the above is the result when a swap is requested
-      and the image in the secondary slot fails to validate, due to a hashing or
-      signing error. This state behaves as State IV with the extra action of
-      marking the image in the primary slot as "OK", to prevent further attempts
-      to swap.
+---
+***Note***
+
+*An important caveat to the above is the result when a swap is requested*
+*and the image in the secondary slot fails to validate, due to a hashing or*
+*signing error. This state behaves as State IV with the extra action of*
+*marking the image in the primary slot as "OK", to prevent further attempts*
+*to swap.*
+
+---
 
 ### [Resumed swaps](#resumed-swaps)
 
@@ -798,13 +813,21 @@
 unwritten, the user can test the image in the secondary slot
 (i.e., transition to state I).
 
-Note1: If the region being copied contains the last sector, then swap status is
-temporarily maintained on scratch for the duration of this operation, always
-using the primary slot's area otherwise.
+---
+***Note***
 
-Note2: The bootloader tries to copy only used sectors (based on largest image
-installed on any of the slots), minimizing the amount of sectors copied and
-reducing the amount of time required for a swap operation.
+*If the region being copied contains the last sector, then swap status is*
+*temporarily maintained on scratch for the duration of this operation, always*
+*using the primary slot's area otherwise.*
+
+---
+***Note***
+
+*The bootloader tries to copy only used sectors (based on largest image*
+*installed on any of the slots), minimizing the amount of sectors copied and*
+*reducing the amount of time required for a swap operation.*
+
+---
 
 The particulars of step 3 vary depending on whether an image is being tested,
 permanently used, reverted or a validation failure of the secondary slot
@@ -914,8 +937,13 @@
 sector index that gets swapped is 63, which corresponds to the exact halfway
 point within the region.
 
-Note: since the scratch area only ever needs to record swapping of the last
-sector, it uses at most min-write-size * 3 bytes for its own status area.
+---
+***Note***
+
+*Since the scratch area only ever needs to record swapping of the last*
+*sector, it uses at most min-write-size * 3 bytes for its own status area.*
+
+---
 
 ## [Reset recovery](#reset-recovery)
 
@@ -1024,8 +1052,13 @@
 If you want to enable and use encrypted images, see:
 [encrypted_images](encrypted_images.md).
 
-Note: Image encryption is not supported when the direct-xip upgrade strategy
-is selected.
+---
+***Note***
+
+*Image encryption is not supported when the direct-xip upgrade strategy*
+*is selected.*
+
+---
 
 ### [Using hardware keys for verification](#hw-key-support)