clash: add page (#10084)

pages/common/clash.md

@@ -0,0 +1,12 @@
+# clash
+
+> A rule-based tunnel in Go.
+> More information: <https://github.com/Dreamacro/clash/wiki>.
+
+- Specify a configuration [d]irectory:
+
+`clash -d {{path/to/directory}}`
+
+- Specify a configuration [f]ile:
+
+`clash -f {{path/to/configuration_file}}`