mdbookコマンドライン引数のtypoを修正

Author: tatsuya6502

.circleci/config.yml

@@ -13,7 +13,7 @@ jobs:
       - run: rustc -V
       - run: mdbook -V
       - run: mdbook test
-      - run: mdbook build --dist-dir docs
+      - run: mdbook build --dest-dir docs
       - run: cargo run --bin lfp src
       # TODO: Run link2print here. (See ci/build.sh on the master branch)
       # - run: TODO