Remove outdated troubleshooting section

The nightly version is pinned since recently

Author: bjorn3

Readme.md

@@ -36,9 +36,3 @@ $ rustc -Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/release/librustc_cod
 * Checked binops ([some missing instructions in cranelift](https://github.com/CraneStation/cranelift/issues/460))
 * Inline assembly ([no cranelift support](https://github.com/CraneStation/cranelift/issues/444), not coming soon)
 * SIMD ([tracked here](https://github.com/bjorn3/rustc_codegen_cranelift/issues/171), some basic things work)
-
-## Troubleshooting
-
-### Can't compile
-
-Try updating your nightly compiler. You can try to use an nightly a day or two older if updating rustc doesn't fix it. If you still can't compile it, please fill an issue.