MINOR: mux-h2/trace: add a new verbosity level "clean"

The "clean" output will be suitable for user and proto-level output
where the internal stuff (state, pointers, etc) is not desired but
just the basic protocol elements.
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 7680ffa..7847230 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -351,9 +351,15 @@
 };
 
 static const struct name_desc h2_trace_decoding[] = {
+#define H2_VERB_CLEAN    1
+	{ .name="clean",    .desc="only user-friendly stuff, generally suitable for level \"user\"" },
+#define H2_VERB_MINIMAL  2
 	{ .name="minimal",  .desc="report only h2c/h2s state and flags, no real decoding" },
+#define H2_VERB_SIMPLE   3
 	{ .name="simple",   .desc="add request/response status line or frame info when available" },
+#define H2_VERB_ADVANCED 4
 	{ .name="advanced", .desc="add header fields or frame decoding when available" },
+#define H2_VERB_COMPLETE 5
 	{ .name="complete", .desc="add full data dump when available" },
 	{ /* end */ }
 };