[FIX] grammatical structure of phrase (#49660)

docs/docsite/rst/dev_guide/style_guide/basic_rules.rst

@@ -42,7 +42,7 @@ Avoid redundant prepositional phrases
 Prepositional phrases, the combination of a preposition with a noun phrase, are among the worst offenders in making text long and tiresome to read. Often, it is possible to replace an entire phrase with a single word.
 
     Use now instead of at this point in time.
-    Use suddenly instead of all of the sudden. 
+    Use suddenly instead of all of a sudden. 
 
 Avoid verbosity
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