Create help sections for build, install, resolve, and index (#5693)
Part of #4454
e.g.
```
$ uv add --help
Add one or more packages to the project requirements
Usage: uv add [OPTIONS] <REQUIREMENTS>...
Arguments:
<REQUIREMENTS>... The packages to add, as PEP 508 requirements (e.g., `ruff==0.5.0`)
Options:
--dev Add the requirements as development dependencies
--optional <OPTIONAL> Add the requirements to the specified optional dependency group
--no-editable Don't add the requirements as editables
--raw-sources Add source requirements to `project.dependencies`, rather than `tool.uv.sources`
--rev <REV> Specific commit to use when adding from Git
--tag <TAG> Tag to use when adding from git
--branch <BRANCH> Branch to use when adding from git
--extra <EXTRA> Extras to activate for the dependency; may be provided more than once
--locked Assert that the `uv.lock` will remain unchanged
--frozen Add the requirements without updating the `uv.lock` file
--package <PACKAGE> Add the dependency to a specific package in the workspace
-p, --python <PYTHON> The Python interpreter into which packages should be installed. [env: UV_PYTHON=]
Index options:
-i, --index-url <INDEX_URL> The URL of the Python package index (by default: <https://pypi.org/simple>) [env: UV_INDEX_URL=]
--extra-index-url <EXTRA_INDEX_URL> Extra URLs of package indexes to use, in addition to `--index-url` [env: UV_EXTRA_INDEX_URL=]
-f, --find-links <FIND_LINKS> Locations to search for candidate distributions, in addition to those found in the registry indexes
--no-index Ignore the registry index (e.g., PyPI), instead relying on direct URL dependencies and those provided via `--find-links`
--index-strategy <INDEX_STRATEGY> The strategy to use when resolving against multiple index URLs [env: UV_INDEX_STRATEGY=] [possible values: first-index, unsafe-first-match, unsafe-best-match]
--keyring-provider <KEYRING_PROVIDER> Attempt to use `keyring` for authentication for index URLs [env: UV_KEYRING_PROVIDER=] [possible values: disabled, subprocess]
Resolver options:
-U, --upgrade Allow package upgrades, ignoring pinned versions in any existing output file
-P, --upgrade-package <UPGRADE_PACKAGE> Allow upgrades for a specific package, ignoring pinned versions in any existing output file
--resolution <RESOLUTION> The strategy to use when selecting between the different compatible versions for a given package requirement [env: UV_RESOLUTION=] [possible values: highest, lowest, lowest-direct]
--prerelease <PRERELEASE> The strategy to use when considering pre-release versions [env: UV_PRERELEASE=] [possible values: disallow, allow, if-necessary, explicit, if-necessary-or-explicit]
--exclude-newer <EXCLUDE_NEWER> Limit candidate packages to those that were uploaded prior to the given date [env: UV_EXCLUDE_NEWER=]
Installer options:
--reinstall Reinstall all packages, regardless of whether they're already installed. Implies `--refresh`
--reinstall-package <REINSTALL_PACKAGE> Reinstall a specific package, regardless of whether it's already installed. Implies `--refresh-package`
--link-mode <LINK_MODE> The method to use when installing packages from the global cache [env: UV_LINK_MODE=] [possible values: clone, copy, hardlink, symlink]
--compile-bytecode Compile Python files to bytecode after installation
Build options:
-C, --config-setting <CONFIG_SETTING> Settings to pass to the PEP 517 build backend, specified as `KEY=VALUE` pairs
--no-build Don't build source distributions
--no-build-package <NO_BUILD_PACKAGE> Don't build source distributions for a specific package
--no-binary Don't install pre-built wheels
--no-binary-package <NO_BINARY_PACKAGE> Don't install pre-built wheels for a specific package
Cache options:
-n, --no-cache Avoid reading from or writing to the cache, instead using a temporary directory for the duration of the operation [env: UV_NO_CACHE=]
--cache-dir <CACHE_DIR> Path to the cache directory [env: UV_CACHE_DIR=]
--refresh Refresh all cached data
--refresh-package <REFRESH_PACKAGE> Refresh cached data for a specific package
Python options:
--python-preference <PYTHON_PREFERENCE> Whether to prefer using Python installations that are already present on the system, or those that are downloaded and installed by uv [possible values: only-managed, managed, system, only-system]
--python-fetch <PYTHON_FETCH> Whether to automatically download Python when required [possible values: automatic, manual]
Global options:
-q, --quiet Do not print any output
-v, --verbose... Use verbose output
--color <COLOR_CHOICE> Control colors in output [default: auto] [possible values: auto, always, never]
--native-tls Whether to load TLS certificates from the platform's native certificate store [env: UV_NATIVE_TLS=]
--offline Disable network access, relying only on locally cached data and locally available files
--no-progress Hides all progress outputs when set
--config-file <CONFIG_FILE> The path to a `uv.toml` file to use for configuration [env: UV_CONFIG_FILE=]
--no-config Avoid discovering configuration files (`pyproject.toml`, `uv.toml`) in the current directory, parent directories, or user configuration directories [env: UV_NO_CONFIG=]
-h, --help Print help
-V, --version Print version
Use `uv help add` for more details.
```
