add usage for llgo

Author: tsingbx

cmd/llgo/build_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/build"
 )
 
+use "build [flags] [packages]"
+
 short "Compile packages and dependencies"
 
 flagOff

cmd/llgo/clean_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/clean"
 )
 
+use "clean [flags] [packages]"
+
 short "Remove object files and cached files"
 
 flagOff

cmd/llgo/cmptest_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/run"
 )
 
+use "cmptest [flags] package [arguments...]"
+
 short "Compile and run with llgo, compare result (stdout/stderr/exitcode) with go or llgo.expect; generate llgo.expect file if -gen is specified"
 
 flagOff

cmd/llgo/cppkg_install_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/xtool/cppkg"
 )
 
+use "cppkg install [flags] [packages]"
+
 short "Install a C/C++ package from github.com/goplus/cppkg"
 
 long `Installs a C/C++ package with the given name and version. For example:

cmd/llgo/get_cmd.gox

@@ -13,6 +13,8 @@
  * See the License for the specific language governing permissions and limitations under the License.
  */
 
+use "get [flags] [packages]"
+
 short "Add dependencies to current module and install them"
 
 run args => {

cmd/llgo/gop_autogen.go

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/install"
 )
 
+use "install [flags] [packages]"
+
 short "Compile and install packages and dependencies"
 
 flagOff

cmd/llgo/install_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/run"
 )
 
+use "run [flags] package [arguments...]"
+
 short "Compile and run Go program"
 
 flagOff

cmd/llgo/run_cmd.gox

@@ -17,6 +17,8 @@ import (
 	self "github.com/goplus/llgo/cmd/internal/test"
 )
 
+use "test [flags] package [arguments...]"
+
 short "Compile and run Go test"
 
 flagOff

cmd/llgo/test_cmd.gox

@@ -19,6 +19,8 @@ import (
 	"github.com/goplus/llgo/internal/env"
 )
 
+use "version"
+
 short "Print LLGo version"
 
 run => {