docs(examples): Don't use is_present with subcommands

Apparently, this isn't supported anymore.

examples/08_subcommands.rs

@@ -35,11 +35,6 @@ fn main() {
         )
         .get_matches();
 
-    // You can check if a subcommand was used like normal
-    if matches.is_present("add") {
-        println!("'myapp add' was run.");
-    }
-
     // You can get the independent subcommand matches (which function exactly like App matches)
     if let Some(matches) = matches.subcommand_matches("add") {
         // Safe to use unwrap() because of the required() option

examples/20_subcommands.rs

@@ -85,11 +85,6 @@ fn main() {
 
     // At this point, the matches we have point to git. Keep this in mind...
 
-    // You can check if one of git's subcommands was used
-    if matches.is_present("clone") {
-        println!("'git clone' was run.");
-    }
-
     // You can see which subcommand was used
     if let Some(subcommand) = matches.subcommand_name() {
         println!("'git {}' was used", subcommand);

examples/21_aliases.rs

@@ -17,11 +17,6 @@ fn main() {
         )
         .get_matches();
 
-    // You can check if a subcommand was used like normal
-    if matches.is_present("ls") {
-        println!("'myapp add' was run.");
-    }
-
     // You can get the independent subcommand matches (which function exactly like App matches)
     if let Some(matches) = matches.subcommand_matches("ls") {
         // Safe to use unwrap() because of the required() option