gst-launch: Update man page

Add description for newly add "position" option
19 jobs for launch-pos in 94 minutes and 11 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Preparation
passed #332595
gst indent

00:00:31

passed #332594
manifest

00:00:20

 
  Build
passed #332596
build fedora x86_64

00:07:21

passed #332597
build nodebug fedora x86_64

00:10:29

 
  Test
passed #332598
check fedora

00:04:08

passed #332599
integration testsuites fedora

00:30:24

 
  Full Builds
passed #332601
build cerbero android universal

00:13:47

passed #332602
build cerbero cross win32

00:09:13

passed #332603
build cerbero cross win64

00:04:31

passed #332600
build cerbero fedora x86_64

00:08:01

 
  Full Tests
passed #332608
valgrind bad

00:04:42

passed #332605
valgrind base

00:08:29

passed #332604
valgrind core

00:11:08

passed #332609
valgrind ges

00:03:03

passed #332809
valgrind good

00:15:58

passed #332607
valgrind ugly

00:02:56

failed #332606
valgrind good

00:15:15

 
  Apps
passed #332610
android universal examples

00:07:06

 
  Deploy
passed #332611
documentation

00:04:43