* misc: cleanup for submodules and Makefile

* misc: use ready-to-run submodule
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>

* Recover Ftq Pointer and send miss req to I$ MSHRs
* Instruction reorder is done by Ftq

* TODO: need a solution for fetch-on-miss

difftest: support --no-diff arg to emulate without difftest by nemu

* Difftest should always be instantiated even if "--no-diff" is enabled
* cuz we need in-core info to implement some arguments like "--max-instr" by DPI-C.
* Therefore, instantiation of difftest and nemu-proxy is decoupled.

* Add ZH-Hans readme.md and fix some grammar issues in english readme
Signed-off-by: NClSlaid <cailue@bupt.edu.cn>

* Typo fixes in ZH-Hans.md
Signed-off-by: NClSlaid <cailue@bupt.edu.cn>

* Add link to zh-hans in readme
Signed-off-by: NClSlaid <cailue@bupt.edu.cn>

* build.sc: remove `testOnly`

mill 0.98 added its own `testOnly`. If we keep our version, we can't compile build.sc.
Some people in the WeChat tutorial group have already encountered this issue.

* Pin mill version to 0.9.8

https://github.com/OpenXiangShan/XiangShan/pull/843#issuecomment-868669873

LightSSS: Release single thread version.

* misc: exclude ready-to-run dir in gitignore

* misc: update ready-to-run flow

* misc: update nemu-so

* readme: use nemu-so in ready-to-run

* misc: exclude ready-to-run dir in gitignore

* misc: update ready-to-run flow

* readme: add acknowledgement

* readme: misc

* ftq: only when corresponding write back port is valid can cfiIndex_vec be updated

* ftq: fix a bug updating cfiInfo when multiple wb ports target the same ftqEntry

added arbitration logic on this situation
now we select the write back request with the smallest ftq offset

readme: update readme

* Only ssip in sip is writeable in smode
* Add sip write permission check
* Fix mipReg write logic

In this commit, we add License for XiangShan project.