[llvm][docs] Fix text rendering in external suites section of Test suite guide

Since the "-" was the first character of a newline, it was rendered
as a bullet point when it was supposed to be punctuation.

Author: DavidSpickett

llvm/docs/TestSuiteGuide.md

@@ -377,8 +377,8 @@ The `train` dataset is used by default.
 
 In addition to SPEC, the multimedia frameworks ffmpeg and dav1d can also
 be hooked up as external projects in the same way. By including them in
-llvm-test-suite, a lot more of potentially vectorizable code gets compiled
-- which can catch compiler bugs merely by triggering code generation asserts.
+llvm-test-suite, a lot more of potentially vectorizable code gets compiled -
+which can catch compiler bugs merely by triggering code generation asserts.
 Including them also adds small code correctness tests, that compare the
 output of the compiler generated functions against handwritten assembly
 functions. (On x86, building the assembly requires having the nasm tool