Document our usage of clang-format

README.md

@@ -227,6 +227,15 @@ data, then builds strobealign as it is in your working copy and compares the
 two produced BAM files. The baseline BAM is cached and re-used as long as the
 baseline commit does not change.
 
+## Code formatting
+
+We use [clang-format](https://clang.llvm.org/docs/ClangFormat.html). You can
+manually format a changed file by running
+`clang-format -style=file src/filename.cpp` or (preferably) install
+[pre-commit](https://pre-commit.com/) and run `pre-commit install` to add a
+Git pre-commit hook that will run when you commit your changes and will
+automatically reformat changed files touched by the commit.
+
 
 V0.7 Performance
 ----------------