Clean and regen docs (#401)

diff --git a/docs/dyn/cloudtrace_v1.projects.html b/docs/dyn/cloudtrace_v1.projects.html
index 3c1086c..5b685d1 100644
--- a/docs/dyn/cloudtrace_v1.projects.html
+++ b/docs/dyn/cloudtrace_v1.projects.html
@@ -121,7 +121,38 @@
                 # to use a consistent name, which makes it easier to correlate
                 # cross-trace spans.
             "labels": { # Collection of labels associated with the span. Label keys must be less than
-                # 128 bytes. Label values must be less than 16 kilobytes.
+                # 128 bytes. Label values must be less than 16 kilobytes (10MB for
+                # `/stacktrace` values).
+                #
+                # Some predefined label keys exist, or you may create your own. When creating
+                # your own, we recommend the following formats:
+                #
+                # * `/category/product/key` for agents of well-known products (e.g.
+                #   `/db/mongodb/read_size`).
+                # * `short_host/path/key` for domain-specific keys (e.g.
+                #   `foo.com/myproduct/bar`)
+                #
+                # Predefined labels include:
+                #
+                # *   `/agent`
+                # *   `/component`
+                # *   `/error/message`
+                # *   `/error/name`
+                # *   `/http/client_city`
+                # *   `/http/client_country`
+                # *   `/http/client_protocol`
+                # *   `/http/client_region`
+                # *   `/http/host`
+                # *   `/http/method`
+                # *   `/http/redirected_url`
+                # *   `/http/request/size`
+                # *   `/http/response/size`
+                # *   `/http/status_code`
+                # *   `/http/url`
+                # *   `/http/user_agent`
+                # *   `/pid`
+                # *   `/stacktrace`
+                # *   `/tid`
               "a_key": "A String",
             },
             "parentSpanId": "A String", # ID of the parent span, if any. Optional.