2.3.0

1. xtheadmempair: Make overlapping register encoding reserved
2. xtheadmempair: Clarify atomicity for load/store-pair instructions
3. xtheadbb: clarify rotate-right instructions
4. xtheadmempair: fix mem index typos in lwd and swd
5. xtheadmemidx: fix memidx load/store l{ur}s/{ur} description errors in RV64/RV32
6. Add T-Head VECTOR vendor extension.

2.2.2

1. Fix descriptions of mulsh, mulsw and th.ff1, and th.ff[01] on RV32.
2. Add extension versioning

2.2.1

1. Fix encode mistake of XTheadFmv
2. Fix some description of TheadSync

2.2.0

1. Fix some incorrect descriptions.
2. Add XTheadVdot vector extension.

2.1.0

Add new extension 'xtheadfmv' and 'xtheadint'.

2.0.0

Merge pull request #2 from cmuellner/mulah-fix

Small corrections and simplifications for xtheadmac and xtheadmemidx