[Doc][Backport] Unit qualifier is required 6.8 (#11780)

* Note that unit qualifier is required for config.reload.interval

* Update description in logstash.yml

Author: karenzone

config/logstash.yml

@@ -77,6 +77,9 @@
 # config.reload.automatic: false
 #
 # How often to check if the pipeline configuration has changed (in seconds)
+# Note that the unit value (s) is required. Values without a qualifier (e.g. 60) 
+# are treated as nanoseconds.
+# Setting the interval this way is not recommended and might change in later versions.
 #
 # config.reload.interval: 3s
 #

docs/static/breaking-changes.asciidoc

@@ -48,6 +48,7 @@ These changes can impact any instance of Logstash and are plugin agnostic, but o
 
 * The setting `config.reload.interval` has been changed to use time value strings such as `5m`, `10s` etc.
   Previously, users had to convert this to a millisecond time value themselves.
+  Note that the unit qualifier (`s`) is required.
 
 [float]
 ===== RPM/Deb package changes

docs/static/reloading-config.asciidoc

@@ -17,7 +17,9 @@ in  configuration settings from the command-line.
 
 By default, Logstash checks for configuration changes every 3 seconds. To change this interval,
 use the `--config.reload.interval <interval>` option,  where `interval` specifies how often Logstash
-checks the config files for changes. 
+checks the config files for changes (in seconds). 
+
+Note that the unit qualifier (`s`) is required.
 
 If Logstash is already running without auto-reload enabled, you can force Logstash to
 reload the config file and restart the pipeline by sending a SIGHUP (signal hangup) to the

docs/static/running-logstash-command-line.asciidoc

@@ -166,6 +166,7 @@ With this command, Logstash concatenates three config files, `/tmp/one`, `/tmp/t
 
 *`--config.reload.interval RELOAD_INTERVAL`*::
   How frequently to poll the configuration location for changes. The default value is "3s".
+  Note that the unit qualifier (`s`) is required.
 
 *`--http.host HTTP_HOST`*::
   Web API binding host. This option specifies the bind address for the metrics REST endpoint. The default is "127.0.0.1".

docs/static/settings-file.asciidoc

@@ -133,7 +133,7 @@ The `logstash.yml` file includes the following settings. If you are using X-Pack
 | `false`
 
 | `config.reload.interval`
-| How often in seconds Logstash checks the config files for changes.
+| How often in seconds Logstash checks the config files for changes. Note that the unit qualifier (`s`) is required.
 | `3s`
 
 | `config.debug`