Add help note for the gerber vs gerbers, and make "pos" obvious

Will add more strings in v8 I guess to avoid too many sneaky string additions :P

kicad/cli/command_export_pcb_gerber.cpp

@@ -36,6 +36,8 @@ CLI::EXPORT_PCB_GERBER_COMMAND::EXPORT_PCB_GERBER_COMMAND( const std::string& aN
 {
     addLayerArg( true );
 
+    m_argParser.add_description( UTF8STDSTR( _( "Plot given layers to a single gerber file" ) ) );
+
     m_argParser.add_argument( "-erd", ARG_EXCLUDE_REFDES )
             .help( UTF8STDSTR( _( "Exclude the reference designator text" ) ) )
             .implicit_value( true )

kicad/cli/command_export_pcb_gerbers.cpp

@@ -38,6 +38,9 @@ CLI::EXPORT_PCB_GERBERS_COMMAND::EXPORT_PCB_GERBERS_COMMAND() :
 {
     m_requireLayers = false;
 
+    m_argParser.add_description( UTF8STDSTR( _( "Plot multiple gerbers for a PCB, including the "
+                                                "ability to use stored board plot settings" ) ) );
+
     m_argParser.add_argument( "-cl", ARG_COMMON_LAYERS )
             .default_value( std::string() )
             .help( UTF8STDSTR(

kicad/cli/command_export_pcb_pos.cpp

@@ -41,6 +41,8 @@
 
 CLI::EXPORT_PCB_POS_COMMAND::EXPORT_PCB_POS_COMMAND() : EXPORT_PCB_BASE_COMMAND( "pos" )
 {
+    m_argParser.add_description( UTF8STDSTR( _( "Export footprint position file" ) ) );
+
     m_argParser.add_argument( ARG_SIDE )
             .default_value( std::string( "both" ) )
             .help( UTF8STDSTR( _(

kicad/cli/command_export_sch_pythonbom.cpp

@@ -31,6 +31,8 @@
 CLI::EXPORT_SCH_PYTHONBOM_COMMAND::EXPORT_SCH_PYTHONBOM_COMMAND() :
         EXPORT_PCB_BASE_COMMAND( "python-bom" )
 {
+    m_argParser.add_description( UTF8STDSTR( _( "Export the legacy bom xml format used in the "
+                                                "schematic editor with python scripts" ) ) );
 }