devapp: update burndown chart to track 1.14 milestone
devapp: update burndown chart to track 1.14 milestone

Change-Id: I3e447c6b3057a66012180dbc11eda29f8db46c7e
Reviewed-on: https://go-review.googlesource.com/c/build/+/193877
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,golang/build,golang/build,golang/build