Base: Add man page for nohup

Author: https://github.com/kemzeb
Commit: https://github.com/SerenityOS/serenity/commit/0c41867ad5
Pull-request: https://github.com/SerenityOS/serenity/pull/19743
Reviewed-by: https://github.com/tcl3

Base/usr/share/man/man1/nohup.md

@@ -0,0 +1,30 @@
+## Name
+
+nohup - Invoke a utility that will ignore SIGHUPs
+
+## Synopsis
+
+```sh
+$ nohup <utility> [args...]
+```
+
+## Description
+`nohup` will invoke `utility` given an optional list of `args`, where at the time of the invocation it will ignore the SIGHUP signal.
+
+If the standard output is a tty, `utility` will append its standard output to the end of the file **nohup.out** in the current directory. If **nohup.out** fails to be created or opened for
+appending, `utility`'s standard output will instead be appended to the end of the file **$HOME/nohup.out**. If this also fails, `utility` won't be invoked. **nohup.out**'s
+permission bits are set to S_IRUSR | S_IWUSR when it is created.
+
+If standard error is a tty, one out of the following will occur:
+1. If the standard output is open but not a tty, `utility` will redirect its standard error to its standard output.
+2. If the standard output is a tty or is closed, standard error shall be appended to the end of **nohup.out** as described above.
+
+## Arguments
+
+* `utility`: Utility to be invoked
+* `args`: Arguments to pass to `utility`
+
+## Exit Status
+
+* 126 - `utility` was found but could not be invoked.
+* 127 - Either `utility` could not be found or an error occurred in `nohup`.