ncdu: move from linux to common (#7814)

pages/common/ncdu.md

@@ -0,0 +1,24 @@
+# ncdu
+
+> Disk usage analyzer with an ncurses interface.
+> More information: <https://manned.org/ncdu>.
+
+- Analyze the current working directory:
+
+`ncdu`
+
+- Colorize output:
+
+`ncdu --color {{dark|off}}`
+
+- Analyze a given directory:
+
+`ncdu {{path/to/directory}}`
+
+- Save results to a file:
+
+`ncdu -o {{path/to/file}}`
+
+- Exclude files that match a pattern, argument can be given multiple times to add more patterns:
+
+`ncdu --exclude '{{*.txt}}'`