csh: add page (#7420)

pages/common/csh.md

@@ -0,0 +1,20 @@
+# csh
+
+> The shell (command interpreter) with C-like syntax.
+> More information: <https://www.mkssoftware.com/docs/man1/csh.1.asp>.
+
+- Start an interactive shell session:
+
+`csh`
+
+- Start an interactive shell session without loading startup configs:
+
+`csh -f`
+
+- Execute a [c]ommand:
+
+`csh -c "{{command}}"`
+
+- Execute a script:
+
+`csh {{path/to/script.csh}}`