Update README.md and some parameter's descriptions

README.md

@@ -83,7 +83,7 @@ mvn clean package -P executable
 This will generate output with collected stats of all processes (should be run as root) every 3 seconds:
 
 ```
-bin/pgio
+bin/pgio -D <postgresql data dir>
 ```
 
 ## Options
@@ -91,17 +91,23 @@ bin/pgio
 ```
 Option                   Description                                           
 ------                   -----------                                           
+-D <String>              Specifies the file system location of the database    
+                           configuration files. If this is omitted, the        
+                           environment variable PGDATA is used.                
+-a, --advanced           Enable advanced options                               
+-d, --debug              Show debug messages                                   
 -g, --group <String>     Group results using specified group configuration file
+                           (advanced option)                                   
 -h, --help               Displays this help message and quit                   
 -i, --interval <String>  Interval in milliseconds to gather stats (default:    
                            3000)                                               
+--no-print-header        Suppress print of CSV header                          
 -o, --show-other         Print read/write data not accounted by any listed     
                            process                                             
---ppid <String>          Parent pid of the process to scan (if not specified   
-                           will scan all processes)                             
---print-header           Print header                                          
+--ppid <String>          Parent pid of the process to scan (advanced option)   
+--prometheus-format      Print output in prometheus format                     
 -s, --show-system        Print read/write data for the whole system            
--v, --version            Show version and quit     
+-v, --version            Show version and quit                                 
 ```
 
 ### Group configuration file

main/src/main/java/com/ongres/pgio/main/Main.java

@@ -131,16 +131,12 @@ public class Main {
         "Enable advanced options");
     parser.acceptsAll(Lists.newArrayList("prometheus-format"), 
         "Print output in prometheus format");
-    parser.acceptsAll(Lists.newArrayList("all-processes"), 
-        "Enable advanced options")
-      .availableIf("advanced");
     parser.acceptsAll(Lists.newArrayList("ppid"), 
-        "Parent pid of the process to scan"
-        + " (if not specified will collect stats from all processes)")
+        "Parent pid of the process to scan (advanced option)")
       .availableIf("advanced")
       .withRequiredArg();
     parser.acceptsAll(Lists.newArrayList("g", "group"), 
-        "Group results using specified group configuration file")
+        "Group results using specified group configuration file (advanced option)")
       .availableIf("advanced")
       .withRequiredArg();
     return parser;