speed-test: add page (#5339)

pages/common/speed-test.md

@@ -0,0 +1,20 @@
+# speed-test
+
+> Test your internet connection speed and ping using speedtest.net from the CLI.
+> More information: <https://github.com/sindresorhus/speed-test>.
+
+- Test your internet connection and ping speed:
+
+`speed-test`
+
+- Output the results as JSON:
+
+`speed-test --json`
+
+- Output the results in megabytes per second (MBps):
+
+`speed-test --bytes`
+
+- Output more detailed information:
+
+`speed-test --verbose`