pg_dumpall: update page (#13623)

Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>
Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>

pages/common/pg_dumpall.md

@@ -9,19 +9,15 @@
 
 - Dump all databases using a specific username:
 
-`pg_dumpall --username={{username}} > {{path/to/file.sql}}`
+`pg_dumpall {{-U|--username}} {{username}} > {{path/to/file.sql}}`
 
 - Same as above, customize host and port:
 
 `pg_dumpall -h {{host}} -p {{port}} > {{output_file.sql}}`
 
-- Dump all databases into a custom-format archive file with moderate compression:
-
-`pg_dumpall -Fc > {{output_file.dump}}`
-
 - Dump only database data into an SQL-script file:
 
-`pg_dumpall --data-only > {{path/to/file.sql}}`
+`pg_dumpall {{-a|--data-only}} > {{path/to/file.sql}}`
 
 - Dump only schema (data definitions) into an SQL-script file: