fix: grammar mistakes

first/explain/comments/main.go

@@ -13,7 +13,7 @@ import "fmt"
 /*
 main function
 Go executes this program using this function.
-There should be only one main file in a main package.
+There should be only one main file in the main package.
 Executable programs are also called as "commands".
 */
 func main() {

first/explain/packages/what/main.go

@@ -17,7 +17,7 @@ func main() {
 
 	// Here, `main()` can access `bye()` and `hey()`
 
-	// It's because: bye.go, hey.go and main.go
+	// It's because bye.go, hey.go and main.go
 	//   are in the main package.
 
 	bye()

first/first/exercises/02/exercise.md

@@ -1,7 +1,7 @@
 // ---------------------------------------------------------
 // EXERCISE
-//  Print your GOPATH using `go env` tool
+//  Print your GOPATH using the `go env` tool
 //
 // EXPECTED OUTPUT
 //  The physical folder path that is referenced by $GOPATH
-// ---------------------------------------------------------
+// ---------------------------------------------------------

first/first/questions/03-run-your-first-program-questions.md

@@ -32,7 +32,7 @@
 
 
 ## Which one below is true for runtime?
-1. It happens when your program starts running in a computer *CORRECT*
+1. It happens when your program starts running on a computer *CORRECT*
 2. It happens while your program is being compiled
 
 
@@ -54,4 +54,4 @@
 >
 > **3:** Running can only happen after the compile-time
 >
->
+>