fix: typos, grammar, and spelling in docs and code (#2735)
* fix: typos, grammar, and spelling in docs and code
- docs/http.md: fix preposition 'to deploying' -> 'on deploying', add missing article
- docs/wsl2/wsl2.md: fix typo 'you NVIDIA' -> 'your NVIDIA'
- docs/python.md: fix awkward phrasing and verb agreement in setup() description
- docs/deploy.md: fix inconsistent heading level for --host section
- docs/training.md: add missing 'self' parameter in train() method example
- docs/notebooks.md: update deprecated python_packages to python_requirements
- pkg/cli/build.go: fix typo 'sing Epoch' -> 'since Epoch'
- pkg/cli/run.go, serve.go, predict.go: fix duplicate word 'but but'
- python/cog/schema.py: remove extra space before period in docstrings
- python/cog/_inspector.py: fix hyphenation 'error prone' -> 'error-prone'
- python/cog/command/openapi_schema.py: simplify redundant error message
* docs: add clear reminder to run mise run docs:llm when updating docs
