loki_datasource: add documentation to label_format and line_format (#31710) (#31746)

* add documentation to label_format and line_format

* fix linting

* Remove extra space

(cherry picked from commit 0b6b8de6f8)

Co-authored-by: Caleb Collins-Parks <46505081+caleb15@users.noreply.github.com>

public/app/plugins/datasource/loki/syntax.ts

@@ -79,12 +79,14 @@ export const PIPE_OPERATORS: CompletionItem[] = [
   {
     label: 'label_format',
     insertText: 'label_format',
-    documentation: 'Only available in Loki 2.0+.',
+    documentation:
+      'Use to rename, modify or add labels. For example, | label_format foo=bar . Only available in Loki 2.0+.',
   },
   {
     label: 'line_format',
     insertText: 'line_format',
-    documentation: 'Only available in Loki 2.0+.',
+    documentation:
+      'Rewrites log line content. For example, | line_format "{{.query}} {{.duration}}" . Only available in Loki 2.0+.',
   },
 ];