Revise SQL example for encode_text function

[kunliuedb]

Updated SQL example for aidb.encode_text function.

What Changed?

Update the sql as the given example returns an error with the No function matches the given name and argument types

edb_admin=# SELECT aidb.encode_text(
edb_admin(#     input   => 'What is pgvector?',
edb_admin(#     options => '{"model": "my_embedding_model"}'
edb_admin(# );
ERROR:  function aidb.encode_text(input => unknown, options => unknown) does not exist
LINE 1: SELECT aidb.encode_text(
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

[nidhibhammar]

LGTM. Shall I merge?

[nidhibhammar]

LGTM. Shall I merge?

@kunliuedb Shall I merge this PR?