CLang is required to install, but not in Readme.md

[sotrh]

While trying to install mevi to my PopOS machine I got the following error:

error: failed to run custom build command for `userfaultfd-sys v0.4.2 (https://github.com/fasterthanlime/userfaultfd-rs?rev=e9160a896f7d8d80c8b0943480885598bd698d0#e9160a89)`

Caused by:
  process didn't exit successfully: `/home/sotrh/code/mevi/target/release/build/userfaultfd-sys-fcd893f786207cc7/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at 'Unable to find libclang: "couldn't find any valid shared libraries matching: ['libclang.so', 'libclang-*.so', 'libclang.so.*', 'libclang-*.so.*'], set the `LIBCLANG_PATH` environment variable to a path where one of these files can be found (invalid: [])"', /home/sotrh/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.60.1/src/lib.rs:2172:31
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: failed to compile `mevi v0.1.0 (/home/sotrh/code/mevi/crates/mevi)`, intermediate artifacts can be found at `/home/sotrh/code/mevi/target`
error: Recipe `install` failed on line 7 with exit code 101

Doing sudo apt install clang fixed the issue, but the Readme should include that CLang is required to install this project.

[fasterthanlime]

the Readme should include that CLang is required to install this project.

Not to be cliché, but pull requests welcome!

That said, I think the error message worked really well here, better to have it there than in a README most probably won't read 🤷