streamlink: add page (#4242)

* streamlink: add page

* Edit with suggestions from PR

pages/common/streamlink.md

@@ -0,0 +1,36 @@
+# streamlink
+
+> Extracts streams from various services and pipes them into a video player of choice.
+> More information: <https://streamlink.github.io>.
+
+- Attempt to extract streams from the URL specified, and if it's successful, print out a list of available streams to choose from:
+
+`streamlink {{example.com/stream}}`
+
+- Open a stream with the specified quality:
+
+`streamlink {{example.com/stream}} {{720p60}}`
+
+- Select the highest or lowest available quality:
+
+`streamlink {{example.com/stream}} {{best|worst}}`
+
+- Specify which player to use to feed stream data to (VLC is used by default if found):
+
+`streamlink --player={{mpv}} {{example.com/stream}} {{best}}`
+
+- Specify the amount of time to skip from the beginning of the stream. For live streams, this is a negative offset from the end of the stream (rewind):
+
+`streamlink --hls-start-offset {{[HH:]MM:SS}} {{example.com/stream}} {{best}}`
+
+- Skip to the beginning of a live stream, or as far back as possible:
+
+`streamlink --hls-live-restart {{example.com/stream}} {{best}}`
+
+- Write stream data to a file instead of playing it:
+
+`streamlink --output {{path/to/file.ts}} {{example.com/stream}} {{best}}`
+
+- Open the stream in the player, while at the same time writing it to a file:
+
+`streamlink --record {{path/to/file.ts}} {{example.com/stream}} {{best}}`