docs: fix extra backtick typo (#719)

Author: stdavis

README.md

@@ -459,7 +459,7 @@ strings that they parse.
   in descending order when passed to `Array.sort()`.
 * `compareBuild(v1, v2)`: The same as `compare` but considers `build` when two versions
   are equal.  Sorts in ascending order if passed to `Array.sort()`.
-* `compareLoose(v1, v2)`: Short for ``compare(v1, v2, { loose: true })`.
+* `compareLoose(v1, v2)`: Short for `compare(v1, v2, { loose: true })`.
 * `diff(v1, v2)`: Returns the difference between two versions by the release type
   (`major`, `premajor`, `minor`, `preminor`, `patch`, `prepatch`, or `prerelease`),
   or null if the versions are the same.