GitLab

* Validation split added: custom data files

Validation split added in case of no validation file and loading custom data

* Updated documentation with custom file usage

Updated documentation with custom file usage

* Update README.md

* Update README.md

* Update README.md

* Made some suggested stylistic changes

* Used logger instead of print.
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Made similar changes to add validation split

In case of a missing validation file, a validation split will be used now.

* max_train_samples to be used for training only

max_train_samples got misplaced, now corrected so that it is applied on training data only, not whole data.

* styled

* changed ordering

* Improved language of documentation
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Improved language of documentation
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Fixed styling issue

* Update run_mlm.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>