Fixes missing schedule in the sample SEG training

[EvgenyM]

Motivation

Running the command python tools/train.py configs/textrecog/seg/seg_r31_1by16_fpnocr_toy_dataset.py --work-dir seg from the "Getting Started" section leads to an issue with missing "checkpoint_config" parameter. This PR aims to fix this issue so that those doing the tutorial have a smoother experience.

Modification

This PR adds a training schedule to the SEG toy dataset configuration, which allows to successfully execute the example training command.

Checklist

Before PR:

• [x] I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• [x] Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• [ ] Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• [ ] New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• [ ] The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• [ ] If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects.
• [ ] CLA has been signed and all committers have signed the CLA in this PR.

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[xinke-wang]

Hi @EvgenyM , thank you for your contribution; would you like to sign the CLA shown above, so we can accept the contribution?

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