Fixed #21035 -- Changed docs to treat the acronym SQL phonetically.

The documentation and comments now all use 'an' to
refer to the word SQL and not 'a'.

docs/internals/contributing/writing-documentation.txt

@@ -78,6 +78,10 @@ documentation:
 
 * **MySQL**, **PostgreSQL**, **SQLite**
 
+* **SQL** -- when referring to SQL, the expected pronunciation should be
+  "Ess Queue Ell" and not "sequel". Thus in a phrase like "Returns an
+  SQL expression", "SQL" should be preceded by "an" and not "a".
+
 * **Python** -- when referring to the language, capitalize Python.
 
 * **realize**, **customize**, **initialize**, etc. -- use the American