List of user guide issues

- [x] demonstrate re-usable custom types https://github.com/common-workflow-language/common-workflow-language/issues/438
- [ ] demonstrate use of scicrunch.org to find IRIs for SoftwareRequirement https://github.com/common-workflow-language/common-workflow-language/issues/437
- [x] add `#!/usr/bin/env cwl-runner` to user guide and examples https://github.com/common-workflow-language/common-workflow-language/issues/436
- [ ] document optional enum syntax https://github.com/common-workflow-language/common-workflow-language/issues/392
- [ ] document in user guide that multiple parameter references and string concatenation are possible without InlineJavascript https://github.com/common-workflow-language/common-workflow-language/issues/389
- [ ] Review SMC_RNA docs for inclusion with user guide https://github.com/common-workflow-language/common-workflow-language/issues/388
- [x] add (link to) reference implementation installation instructions https://github.com/common-workflow-language/common-workflow-language/issues/367
- [ ] better document the 'default' and 'valueFrom' fields on WorkflowStepInput https://github.com/common-workflow-language/common-workflow-language/issues/359
- [ ] capture docker+CWL best practices from Denis Yuen et al. https://github.com/common-workflow-language/common-workflow-language/issues/347
- [ ] Tutorial inconcistencies https://github.com/common-workflow-language/common-workflow-language/issues/318
- [ ] secondaryFiles https://github.com/common-workflow-language/common-workflow-language/issues/270
- [ ] how to reuse custom record types https://github.com/common-workflow-language/common-workflow-language/issues/241
- [ ] Apply the readme checklist https://github.com/common-workflow-language/common-workflow-language/issues/223
- [ ] rework Record inputs, dependent and mutually exclusive parameters https://github.com/common-workflow-language/user_guide/issues/386
- [x] metadata proposal https://github.com/common-workflow-language/common-workflow-language/issues/364