chronic, combine, ifdata, ifne, isutf8: add pages (#12114)

* chronic, combine, ifdata, ifne, isutf8: add pages

---------

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

pages/common/isutf8.md

@@ -0,0 +1,24 @@
+# isutf8
+
+> Check whether text files contain valid UTF-8.
+> More information: <https://joeyh.name/code/moreutils/>.
+
+- Check whether the specified files contain valid UTF-8:
+
+`isutf8 {{path/to/file1 path/to/file2 ...}}`
+
+- Print errors using multiple lines:
+
+`isutf8 --verbose {{path/to/file1 path/to/file2 ...}}`
+
+- Do not print anything to `stdout`, indicate the result merely with the exit code:
+
+`isutf8 --quiet {{path/to/file1 path/to/file2 ...}}`
+
+- Only print the names of the files containing invalid UTF-8:
+
+`isutf8 --list {{path/to/file1 path/to/file2 ...}}`
+
+- Same as `--list` but inverted, i.e., only print the names of the files containing valid UTF-8:
+
+`isutf8 --invert {{path/to/file1 path/to/file2 ...}}`