Changed the README File's Year of Copyright and Changed the calculation in the simple-interest.sh file's calculation line to make it more readible

Author: PheanoukHun

README.md

@@ -13,4 +13,4 @@ Output
    simple interest = p*t*r
 ```
 
-_© 2022 XYZ, Inc._
+_© 2023 XYZ, Inc._

simple-interest.sh

@@ -21,6 +21,6 @@ read r
 echo "Enter time period in years:"
 read t
 
-s=$(expr $p \* $t \* $r / 100)
+s=$$((p * t * r / 100))
 echo "The simple interest is: "
 echo $s