Remove unnecessary backticks

Co-authored-by: Camelid <[email protected]>

Author: jyn514

src/building/bootstrapping.md

@@ -179,7 +179,7 @@ Without it, you can only compile programs with `#![no_core]` -- not terribly use
 
 The reason these need to be different is because they aren't necessarily ABI-compatible:
 there could be a new layout optimizations, changes to MIR, or other changes
-to Rust metadata on nightly that aren't present in `beta`.
+to Rust metadata on nightly that aren't present in beta.
 
 This is also where `--keep-stage 1 library/std` comes into play. Since most
 changes to the compiler don't actually change the ABI, once you've produced a