Update style guide note on files which match OpenSSL.

They match the new style not the old EAY style now. They're also not
likely to be reformatted. It's just the legacy ASN.1 stuff now and we're
intentionally not doing much with those. (The old text was written back
before the SSL stack had been reformatted.)

Change-Id: I4852761b013e8c2688ebc7eaf4970afbdc69e858
Reviewed-on: https://boringssl-review.googlesource.com/8129
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

STYLE.md

@@ -14,10 +14,10 @@ concerned, balance consistency within a module with the benefits of a
 given rule. Module-wide deviations on naming should be respected while
 integer and return value conventions take precedence over consistency.
 
-Some modules have seen few changes, so they still retain the original
-indentation style for now. When editing these, try to retain the
-original style. For Emacs, `doc/c-indentation.el` from OpenSSL may be
-helpful in this.
+Modules from OpenSSL's legacy ASN.1 and X.509 stack are retained for
+compatibility and left largely unmodified. To ease importing patches from
+upstream, they match OpenSSL's new indentation style. For Emacs,
+`doc/openssl-c-indent.el` from OpenSSL may be helpful in this.
 
 
 ## Language