version 5 is now not supported (#1568)

Author: tshepang

src/llvm-coverage-instrumentation.md

@@ -222,13 +222,11 @@ properly-configured variables in LLVM IR, according to very specific
 details of the [_LLVM Coverage Mapping Format_][coverage-mapping-format]
 (Version 6).[^llvm-and-covmap-versions]
 
-[^llvm-and-covmap-versions]: The Rust compiler (as of <!-- date-check --> December 2021)
-supports _LLVM Coverage Mapping Format_ Version 5 or 6. Version 5
-was introduced in _LLVM 12_,
-which is (as of <!-- date-check: December 2021--> this writing) the minimum LLVM
-version supported by the current version of Rust. Version 6 was introduced in
-_LLVM 13_, which is currently the default LLVM version for Rust. The Rust
-compiler will automatically use the most up-to-date coverage mapping format
+[^llvm-and-covmap-versions]:
+The Rust compiler (as of <!-- date-check: --> Jan 2023) supports _LLVM Coverage Mapping Format_ 6.
+It was introduced in _LLVM 13_, which is, as of <!-- date-check: Jan 2023 --> this writing,
+the minimum supported LLVM version.
+The Rust compiler will automatically use the most up-to-date coverage mapping format
 version that is compatible with the compiler's built-in version of LLVM.
 
 ```rust