Some code snippets in the docs had the task and pipeline names with capital letters that were invalid.

Changes

Change the task and pipeline names to all lowercase letters in the following files.

• taskrun.md
• pipelinerun.md

There was a space in the step name in the pipelinerun.md. It is removed, too

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes tests (if functionality changed/added)
• Includes docs (if user facing)
• Commit messages follow commit message best practices

See the contribution guide for more details.

Double check this list of stuff that's easy to miss:

• If you are adding a new binary/image to the cmd dir, please update
  the release Task to build and release this image.

Reviewer Notes

If API changes are included, additive changes must be approved by at least two OWNERS and backwards incompatible changes must be approved by more than 50% of the OWNERS, and they must first be added in a backwards compatible way.

Release Notes

Describe any user facing changes here, or delete this block.

Examples of user facing changes:
- API changes
- Bug fixes
- Any changes in behavior