Style guide: mention placement of & for reference types

Change-Id: I87d474f81ecb33747e8b3a04ed3e71d1c07139ec
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/81247
Auto-Submit: Lily Chen <chlily@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Lily Chen <chlily@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

STYLE.md

diff --git a/STYLE.md b/STYLE.md
index 1b6bd0b..29c0dd7 100644
--- a/STYLE.md
+++ b/STYLE.md
@@ -33,14 +33,16 @@
 
 Comments should be `// C99-style` for consistency with C++.
 
-When declaring pointer types, `*` should be placed next to the variable name,
-not the type. So
+When declaring pointer or reference types, `*` or `&` should be placed next to
+the variable name, not the type. So
 
     uint8_t *ptr;
+    const auto &blah;
 
 not
 
     uint8_t* ptr;
+    const auto& blah;
 
 Rather than `malloc()` and `free()`, use the wrappers `OPENSSL_malloc()`
 and `OPENSSL_free()`. Use the standard C `assert()` function freely.