update tpu docs

Author: nt

g3doc/user_guide/tpu.md

@@ -38,7 +38,7 @@ impact.
 
 ### Supported TPUs {#tpu-models}
 
-gVisor currently supports TPU models: V4lite V4pod, V5, and V5e.
+gVisor currently supports TPU models: V4, V4lite, V4pod, V5e, V5p, V6e, and V6p.
 [open a GitHub issue](https://github.com/google/gvisor/issues/new?labels=type%3A+enhancement,area%3A+gpu&template=bug_report.yml)
 if you want support for another TPU model. gVisor only supports "1VM" TPU
 shapes.