fixups in the tutorial
also add a section about compiling programs because some found it surprising not to have one

R=rsc
CC=go-dev
http://go/go-review/1018011
diff --git a/doc/progs/sortmain.go b/doc/progs/sortmain.go
index 63d68ff..8f6b106 100644
--- a/doc/progs/sortmain.go
+++ b/doc/progs/sortmain.go
@@ -29,8 +29,8 @@
 
 type day struct {
 	num        int;
-	short_name string;
-	long_name  string;
+	shortName  string;
+	longName   string;
 }
 
 type dayArray struct {
@@ -56,7 +56,7 @@
 		panic()
 	}
 	for _, d := range data {
-		fmt.Printf("%s ", d.long_name)
+		fmt.Printf("%s ", d.longName)
 	}
 	fmt.Printf("\n")
 }