Add docs for constraint-dependencies and override-dependencies (#6596)

Add missing portions of documents reported in #6518 and #5248(Comment).

## Summary

<img width="600" alt="override"
src="https://github.com/user-attachments/assets/062f0036-8672-4c68-b21c-aebdeb79b58b">

<img width="600" alt="constraint"
src="https://github.com/user-attachments/assets/f5ef1aa2-0662-4352-a1a0-3af1127fb7fb">

crates/uv-settings/src/settings.rs

@@ -40,13 +40,9 @@ pub struct Options {
     pub top_level: ResolverInstallerOptions,
     #[option_group]
     pub pip: Option<PipOptions>,
-    #[cfg_attr(
-        feature = "schemars",
-        schemars(
-            with = "Option<Vec<String>>",
-            description = "PEP 508 style requirements, e.g. `ruff==0.5.0`, or `ruff @ https://...`."
-        )
-    )]
+
+    // NOTE(charlie): These fields are shared with `ToolUv` in
+    // `crates/uv-workspace/src/pyproject.rs`, and the documentation lives on that struct.
     pub override_dependencies: Option<Vec<Requirement<VerbatimParsedUrl>>>,
     pub constraint_dependencies: Option<Vec<Requirement<VerbatimParsedUrl>>>,
 

crates/uv-workspace/src/pyproject.rs

@@ -137,14 +137,66 @@ pub struct ToolUv {
         "#
     )]
     pub environments: Option<SupportedEnvironments>,
+    /// Overrides to apply when resolving the project's dependencies.
+    ///
+    /// Overrides are used to force selection of a specific version of a package, regardless of the
+    /// version requested by any other package, and regardless of whether choosing that version
+    /// would typically constitute an invalid resolution.
+    ///
+    /// While constraints are _additive_, in that they're combined with the requirements of the
+    /// constituent packages, overrides are _absolute_, in that they completely replace the
+    /// requirements of any constituent packages.
+    ///
+    /// !!! note
+    ///     In `uv lock`, `uv sync`, and `uv run`, uv will only read `override-dependencies` from
+    ///     the `pyproject.toml` at the workspace root, and will ignore any declarations in other
+    ///     workspace members or `uv.toml` files.
     #[cfg_attr(
         feature = "schemars",
         schemars(
             with = "Option<Vec<String>>",
-            description = "PEP 508-style requirements, e.g. `ruff==0.5.0`, or `ruff @ https://...`."
+            description = "PEP 508-style requirements, e.g., `ruff==0.5.0`, or `ruff @ https://...`."
         )
     )]
+    #[option(
+        default = r#"[]"#,
+        value_type = "list[str]",
+        example = r#"
+            # Always install Werkzeug 2.3.0, regardless of whether transitive dependencies request
+            # a different version.
+            override-dependencies = ["werkzeug==2.3.0"]
+        "#
+    )]
     pub override_dependencies: Option<Vec<pep508_rs::Requirement<VerbatimParsedUrl>>>,
+    /// Constraints to apply when resolving the project's dependencies.
+    ///
+    /// Constraints are used to restrict the versions of dependencies that are selected during
+    /// resolution.
+    ///
+    /// Including a package as a constraint will _not_ trigger installation of the package on its
+    /// own; instead, the package must be requested elsewhere in the project's first-party or
+    /// transitive dependencies.
+    ///
+    /// !!! note
+    ///     In `uv lock`, `uv sync`, and `uv run`, uv will only read `constraint-dependencies` from
+    ///     the `pyproject.toml` at the workspace root, and will ignore any declarations in other
+    ///     workspace members or `uv.toml` files.
+    #[cfg_attr(
+        feature = "schemars",
+        schemars(
+            with = "Option<Vec<String>>",
+            description = "PEP 508-style requirements, e.g., `ruff==0.5.0`, or `ruff @ https://...`."
+        )
+    )]
+    #[option(
+        default = r#"[]"#,
+        value_type = "list[str]",
+        example = r#"
+            # Ensure that the grpcio version is always less than 1.65, if it's requested by a
+            # transitive dependency.
+            constraint-dependencies = ["grpcio<1.65"]
+        "#
+    )]
     pub constraint_dependencies: Option<Vec<pep508_rs::Requirement<VerbatimParsedUrl>>>,
 }