[show][interfaces] Add proposal for show interfaces flap (sonic-net#3627)

* [show][interfaces] Add proposal for show interfaces history

Signed-off-by: Vaibhav Dahiya <[email protected]>

* change name

Signed-off-by: Vaibhav Dahiya <[email protected]>

* corrections

Signed-off-by: Vaibhav Dahiya <[email protected]>

* add changes

Signed-off-by: Vaibhav Dahiya <[email protected]>

* correct syntax

Signed-off-by: Vaibhav Dahiya <[email protected]>

* fix comments

Signed-off-by: Vaibhav Dahiya <[email protected]>

---------

Signed-off-by: Vaibhav Dahiya <[email protected]>

Author: vdahiya12

doc/Command-Reference.md

@@ -5134,6 +5134,23 @@ This command is to display the link-training status of the selected interfaces.
     Ethernet8      trained          on      up       up
   ```
 
+**show interfaces flap**
+
+The show interfaces flap command provides detailed insights into interface events, including the timestamp of the last link down event and the total flap count (number of times the link has gone up and down). This helps in diagnosing stability and connectivity issues.
+
+- Usage:
+  ```
+  show interfaces flap
+  ```
+- Example:
+  ```
+  admin@sonic:~$ show interfaces flap
+  Interface    Flap Count    Admin    Oper    Link Down TimeStamp (UTC)                                 Link Up TimeStamp (UTC)
+  -----------  ------------  -------  ------  --------------------------------------------------------  -----------------------------------------------------------
+  Ethernet0    5             Up       Up      Last flapped : 2024-10-01 10:00:00 (0 days 00:01:23 ago)  Last Link up: 2024-09-30 10:01:03 UTC (1 days 02:30:15 ago)
+  Ethernet4    Never         Up       Up      Never                                                     Last Link up: 2024-09-30 10:01:03 UTC (1 days 02:30:15 ago)
+  Ethernet8    1             Up       Up      Last flapped : 2024-10-01 10:01:00 (0 days 00:00:23 ago)  Last Link up: 2024-10-02 10:01:03 UTC (5 days 02:30:15 ago)
+  ```
 **show interfaces errors**
 
 The show interface errors command provides detailed statistics and error counters for MAC-level operations on an interface. It displays the status of various operational parameters, error counts, and timestamps for when these errors occurred.