[docs] Slight reword for precision.

The new wording cannot be construed as suggesting the use of
SmallVectorImpl<T> as e.g. a class member (just because the class
happens to be in an interface).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177778 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ProgrammersManual.rst b/docs/ProgrammersManual.rst
index eed12e9..87b8020 100644
--- a/docs/ProgrammersManual.rst
+++ b/docs/ProgrammersManual.rst
@@ -628,7 +628,7 @@
 
 .. note::
 
-   Prefer to use ``SmallVectorImpl<T>`` in interfaces.
+   Prefer to use ``SmallVectorImpl<T>`` as a parameter type.
 
    In APIs that don't care about the "small size" (most?), prefer to use
    the ``SmallVectorImpl<T>`` class, which is basically just the "vector