doc/issue_tracker.txt: various updates

Added missing components.
Fixed some nits.

Signed-off-by: Lou Logan <lou@lrcd.com>

doc/issue_tracker.txt

 FFmpeg's bug/feature request tracker manual
 =================================================
 
-NOTE: This is a draft.
-
 Overview:
 ---------
 
@@ -22,9 +20,9 @@ a mail for every change to every issue.
 (the above does all work already after light testing)
 
 The subscription URL for the ffmpeg-trac list is:
-http(s)://lists.ffmpeg.org/mailman/listinfo/ffmpeg-trac
+https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-trac
 The URL of the webinterface of the tracker is:
-http(s)://trac.ffmpeg.org
+https://trac.ffmpeg.org
 
 Type:
 -----
@@ -42,12 +40,16 @@ feature request / enhancement
     where the current implementation cannot be considered wrong.
 
 license violation
-    ticket to keep track of (L)GPL violations of ffmpeg by others
+    Ticket to keep track of (L)GPL violations of ffmpeg by others.
 
 sponsoring request
     Developer requests for hardware, software, specifications, money,
     refunds, etc.
 
+task
+    A task/reminder such as setting up a FATE client, adding filters to
+    Trac, etc.
+
 Priority:
 ---------
 critical
@@ -66,7 +68,8 @@ important
     don't exist in a past revision or another branch.
 
 normal
-
+   Default setting. Use this if the bug does not match the other
+   priorities or if you are unsure of what priority to choose.
 
 minor
     Bugs about things like spelling errors, "mp2" instead of
@@ -163,14 +166,23 @@ Component:
 avcodec
     issues in libavcodec/*
 
+avdevice
+    issues in libavdevice/*
+
+avfilter
+    issues in libavfilter/*
+
 avformat
     issues in libavformat/*
 
 avutil
     issues in libavutil/*
 
-regression test
-    issues in tests/*
+build system
+    issues in or related to configure/Makefile
+
+documentation
+    issues in or related to doc/*
 
 ffmpeg
     issues in or related to ffmpeg.c
@@ -184,11 +196,23 @@ ffprobe
 ffserver
     issues in or related to ffserver.c
 
-build system
-    issues in or related to configure/Makefile
+postproc
+    issues in libpostproc/*
+
+swresample
+    issues in libswresample/*
 
-regression
-    bugs which were not present in a past revision
+swscale
+    issues in libswscale/*
 
 trac
     issues related to our issue tracker
+
+undetermined
+    default component; choose this if unsure
+
+website
+    issues related to the website
+
+wiki
+    issues related to the wiki