Add a "Cherry picks" line to the release notes

I was confused about the bulleted list on 0.2.2, so I figured it
would be nice tell people what the commit list is.

--
MOS_MIGRATED_REVID=120577721
diff --git a/scripts/release/relnotes_test.sh b/scripts/release/relnotes_test.sh
index 92538ff..9322b5d 100755
--- a/scripts/release/relnotes_test.sh
+++ b/scripts/release/relnotes_test.sh
@@ -113,6 +113,8 @@
 ## Cherry-picking bb59d88
 
 Baseline: 965c392
+
+Cherry picks:
    + bb59d88: RELNOTES[INC]: Remove deprecated "make var" INCDIR
 
 $TEST_INC_CHANGE
@@ -127,6 +129,8 @@
 ## Cherry-picking bb59d88 and 14d905b
 
 Baseline: 965c392
+
+Cherry picks:
    + bb59d88: RELNOTES[INC]: Remove deprecated "make var" INCDIR
    + 14d905b: Add --with_aspect_deps flag to blaze query. This flag
               should produce additional information about aspect
@@ -159,6 +163,8 @@
 
 ```
 Baseline: 965c392
+
+Cherry picks:
    + bb59d88: RELNOTES[INC]: Remove deprecated "make var" INCDIR
 ```
 
@@ -176,6 +182,8 @@
 
 ```
 Baseline: 965c392
+
+Cherry picks:
    + bb59d88: RELNOTES[INC]: Remove deprecated "make var" INCDIR
    + 14d905b: Add --with_aspect_deps flag to blaze query. This flag
               should produce additional information about aspect
@@ -193,6 +201,8 @@
 
 function test_create_revision_information() {
   expected='Baseline: 965c392
+
+Cherry picks:
    + bb59d88: RELNOTES[INC]: Remove deprecated "make var" INCDIR
    + 14d905b: Add --with_aspect_deps flag to blaze query. This flag
               should produce additional information about aspect