feat: Add Docker pre-commit hook

Mostly as an alternative to the src install, but trading host dependency
on Rust with one on Docker.

docs/pre-commit.md

@@ -13,7 +13,8 @@ repos:
 
 The `typos` id installs a prebuilt executable from GitHub releases. If
 one does not exist for the target platform, or if one built from
-sources is preferred, use `typos-src` as the hook id instead.
+sources is preferred, use `typos-docker` (requires Docker), or `typos-src`
+(requires Rust) as the hook id instead.
 
 Be sure to change `rev` to use the desired `typos` git tag or
 revision.