GitLab

* wip: adding tf example for semantic segmentation guide

* completed the working example in tf

* make style

* Update docs/source/en/tasks/semantic_segmentation.mdx
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update docs/source/en/tasks/semantic_segmentation.mdx
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* fixed a callback doc links
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>