Doc: clarify logfile description (#8013)

The traffic_manager and traffic_server stdout and stderr streams can be
bound via the --bind_stdout and --bind_stderr command line options. If
this is done, then `proxy.config.output.logfile` can be used to identify
that path for log rolling. This change clarifies that the latter
configuration is only for log rolling configuration identification
purposes and that the filename that ATS uses is actually set via the
--bind options.

---

This fixes: #6249

(cherry picked from commit 534c8b3)

doc/admin-guide/files/records.config.en.rst

@@ -213,13 +213,25 @@ System Variables
 
 .. ts:cv:: CONFIG proxy.config.output.logfile  STRING traffic.out
 
-   The name and location of the file that contains warnings, status messages, and error messages produced by the |TS|
-   processes. If no path is specified, then |TS| creates the file in its logging directory.
-
+   This is used for log rolling configuration so |TS| knows the path of the
+   output file that should be rolled. This configuration takes the name of the
+   file receiving :program:`traffic_server` and :program:`traffic_manager`
+   process output that is set via the ``--bind_stdout`` and ``--bind_stderr``
+   :ref:`command-line options <traffic_server>`.
+   :ts:cv:`proxy.config.output.logfile` is used only to identify the name of
+   the output file for log rolling purposes and does not override the values
+   set via ``--bind_stdout`` and ``--bind_stderr``.
+
+   If a filename is passed to this option, then it will be interpreted relative
+   to :ts:cv:`proxy.config.log.logfile_dir`. If a different location is desired,
+   then pass an absolute path to this configuration.
 
 .. ts:cv:: CONFIG proxy.config.output.logfile_perm STRING rw-r--r--
 
-   The log file permissions. The standard UNIX file permissions are used (owner, group, other). Permissible values are:
+   The log file permissions for the file receiving |TS| output, the path of
+   which is configured via the ``--bind_stdout`` and ``--bind_stderr``
+   :ref:`command-line options <traffic_server>`.  The standard UNIX file
+   permissions are used (owner, group, other). Permissible values are:
 
    ===== ======================================================================
    Value Description

doc/appendices/command-line/traffic_manager.en.rst

@@ -41,6 +41,14 @@ Description
 .. option:: --recordsConf FILE
 .. option:: --tsArgs ARGUMENTS
 .. option:: --maxRecords RECORDS
+.. option:: --bind_stdout FILE
+
+The file to which the stdout stream for :program:`traffic_manager` will be bound.
+
+.. option:: --bind_stderr FILE
+
+The file to which the stderr stream for :program:`traffic_manager` will be bound.
+
 .. option:: --version
 
 Signals

doc/appendices/command-line/traffic_server.en.rst

@@ -36,6 +36,14 @@ Options
 
 .. option:: -B TAGS, --action_tags TAGS
 
+.. option:: --bind_stdout FILE
+
+The file to which the stdout stream for |TS| will be bound.
+
+.. option:: --bind_stderr FILE
+
+The file to which the stderr stream for |TS| will be bound.
+
 .. option:: -C 'CMD [ARGS]', --command 'CMD [ARGS]'
 
 Run a |TS| maintenance command. These commands perform various administrative