Address configure clis (#1111)

* remove unnecessary -- in config CLI commands

* add optical and DSP PM min/max spec

doc/platform_api/CMIS_and_C-CMIS_support_for_ZR.md

@@ -779,28 +779,29 @@ configure privisioning settings of the transceivers
 
 - Example (bring module up from low power mode, or bring down module to low power mode):
  ```
- admin@sonic:~# config interface transceiver lpmode Ethernet0 -- enable
+ admin@sonic:~# config interface transceiver lpmode Ethernet0 enable
  Enabling low-power mode for port Ethernet0 ... OK
 
- admin@sonic:~# config interface transceiver lpmode Ethernet0 -- disable
+ admin@sonic:~# config interface transceiver lpmode Ethernet0 disable
  Disabling low-power mode for port Ethernet0 ... OK
  ```
 
 - Example (config the privisioning frequency):
  ```
- admin@sonic:~# config interface transceiver frequency Ethernet0 -- 196025
+ admin@sonic:~# config interface transceiver frequency Ethernet0 196025
  Setting laser frequency to 196025 GHz on port Ethernet0
  ```
 
 - Example (config the privisioning TX power):
+The "--" is needed here because the provisioned value is negative.
  ```
  admin@sonic:~# config interface transceiver tx_power Ethernet0 -- -10.0
  Setting target Tx output power to -10.0 dBm on port Ethernet0
  ```
 
 - Example (config the loopback mode):
  ```
- admin@sonic:~$ config interface transceiver loopback Ethernet0 -- none
+ admin@sonic:~$ config interface transceiver loopback Ethernet0 none
  Setting loopback mode to none
  ```
 
@@ -1049,6 +1050,29 @@ def get_TX_configured_power(port):
 ```
 
 #### 3.2 Get VDM related information
+
+The table below specifies the threshold for important optics and DSP performance metrics:
+
+
+|PM| Min| Max|
+|--|--|--|
+|PreFEC BER|0| 1.25E-2|
+|PostFEC BER| |0|
+|Tx Power (dBm)| | | 
+|Rx Power (dBm)| | | 
+|OSNR (dB/0.1nm)|26| |
+|SNR (dB)|13.6| |
+|CD (ps/nm)| 0| 2400|
+|Frequency Offset (GHz)|-3.6|3.6|
+|peak DGD (ps)| 0| 28|
+|peak PDL (dB)| 0| 3.5|
+|SOP (krad/s)| 0| 50|
+|Case Temperature ($^{o}$C) | |75 |
+|Laser Temperature ($^{o}$C)| |75 |
+| EVM| | |
+
+
+
 - get_VDM
 
 ```get_VDM_page``` function uses ```VDM_TYPE``` dictionary above. It parses all the VDM items defined in the dictionary within a certain VDM page and returns both VDM monitor values and four threshold values related to this VDM item. ```get_VDM``` function combines VDM items from all VDM pages.