Clarify Unit Requirement for Duration Comparison in Label Values

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Description
This update clarifies the requirement for units within the original label value when making a Duration comparison. It ensures that users understand the necessity of including a unit suffix (e.g., 'ms', 'h') for accurate parsing and comparison.

Changes
Updated documentation to specify that the label value must include a unit suffix.
Added examples and notes about using label_format to modify the value and append the unit before comparison.
Motivation and Context
Clarifies the need for units within the original label value when making a Duration comparison, preventing potential parsing errors and improving the accuracy of comparisons.

docs/sources/query/log_queries/_index.md

@@ -223,7 +223,7 @@ For example with `cluster="namespace"` the cluster is the label identifier, the
 We support multiple **value** types which are automatically inferred from the query input.
 
 - **String** is double quoted or backticked such as `"200"` or \``us-central1`\`.
-- **[Duration](https://golang.org/pkg/time/#ParseDuration)** is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
+- **[Duration](https://golang.org/pkg/time/#ParseDuration)** is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h". The value of the label identifier used for comparison must be a string with a unit suffix to be parsed correctly, such as "0.10ms" or "1h30m". Optionally, `label_format` can be used to modify the value and append the unit before making the comparison.
 - **Number** are floating-point number (64bits), such as`250`, `89.923`.
 - **Bytes** is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "42MB", "1.5Kib" or "20b". Valid bytes units are "b", "kib", "kb", "mib", "mb", "gib",  "gb", "tib", "tb", "pib", "pb", "eib", "eb".