Fix typo in receivedamnt variable and _wallet_address parameter for consistency in Sal and allemp contracts.

[adil-techcode]

In the Sal contract, the recievedamnt variable has a typo. It should be corrected to receivedamnt for consistency. and In the addemp function of the allemp contract, the parameter name _wallet_ddress should be corrected to _wallet_address.

Please assign this issue to me under GSSOC'23. Thank You!