Fixes a documentation typo

[chuckha]

Signed-off-by: Chuck Ha chuckh@vmware.com

Without this patch the example output looks like this:

$ go run main2.go 
main.wrapMe
    /Users/cha/test/main2.go:%!d(MISSING)main.main
    /Users/cha/test/main2.go:%!d(MISSING)runtime.main
    /Users/cha/.gimme/versions/go1.11.2.darwin.amd64/src/runtime/proc.go:%!d(MISSING)runtime.goexit
    /Users/cha/.gimme/versions/go1.11.2.darwin.amd64/src/runtime/asm_amd64.s:%!d(MISSING)```

After the change:

$ go run main2.go main.wrapMe /Users/cha/test/main2.go:32 main.main /Users/cha/test/main2.go:19 runtime.main /Users/cha/.gimme/versions/go1.11.2.darwin.amd64/src/runtime/proc.go:201 runtime.goexit /Users/cha/.gimme/versions/go1.11.2.darwin.amd64/src/runtime/asm_amd64.s:1333

[chuckha]

closing in favor of #171