Fix typo in TransformerEncoder and TransformerEncoderLayer documentation (#26230)
Summary:
Fixes a few small typos in the documentation, changing "endocder" to "encoder" and "sequnce" to "sequence"
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26230
Differential Revision: D17910820
Pulled By: vincentqb
fbshipit-source-id: 58c63f8dbbd8e2079201d4485a0d4ef323ecfb49