clean up comment

Author: dwrensha

capnpc/rust.capnp

@@ -2,8 +2,8 @@
 
 annotation name @0xc2fe4c6d100166d0 (field, struct, enum, enumerant, union, group) :Text;
 # Rename something in the generated code. The value that you specify in this
-# annotion must follow capnp capitalization conventions. So, for example,
-# a struct could be named `StructFoo`, even though that will get translated
-# to a `struct_foo` module in the generated Rust code.
+# annotation should follow capnp capitalization conventions. So, for example,
+# a struct should use CamelCase capitalization like `StructFoo`, even though
+# that will get translated to a `struct_foo` module in the generated Rust code.
 #
 # TODO: support annoting more kinds of things with this.