Update link to the training information in build_convert.md
Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @Ferev Can you please review this PR ? Thank you! Hi @LakshmiKalaKadali Can you please resolve conflicts? Thank you! This PR is out of date and no longer necessary, link is no longer broken: https://www.tensorflow.org/lite/microcontrollers/build_convert, so I am closing.
The link to the colab notebook about training is broken and it is now updated with `train.py` in the hello world example.

Thanks.