doc/hooks/haredo: add documentation

Hook introduced in #269767 by @pbsds.

Part of #341479.

doc/hooks/haredo.section.md

@@ -0,0 +1,29 @@
+# `haredo` {#haredo-hook}
+
+This hook uses [the `haredo` command runner](https://sr.ht/~autumnull/haredo/) to build, check, and install the package. It overrides `buildPhase`, `checkPhase`, and `installPhase` by default.
+
+The hook builds its targets in parallel if [`config.enableParallelBuilding`](#var-stdenv-enableParallelBuilding) is set to `true`.
+
+## `buildPhase` {#haredo-hook-buildPhase}
+
+This phase attempts to build the default target.
+
+[]{#haredo-hook-haredoBuildTargets} Targets can be explicitly set by adding a string to the `haredoBuildTargets` list.
+
+[]{#haredo-hook-dontUseHaredoBuild} This behavior can be disabled by setting `dontUseHaredoBuild` to `true`.
+
+## `checkPhase` {#haredo-hook-checkPhase}
+
+This phase searches for the `check.do` or `test.do` targets, running them if they exist.
+
+[]{#haredo-hook-haredoCheckTargets} Targets can be explicitly set by adding a string to the `haredoCheckTargets` list.
+
+[]{#haredo-hook-dontUseHaredoCheck} This behavior can be disabled by setting `dontUseHaredoCheck` to `true`.
+
+## `installPhase` {#haredo-hook-installPhase}
+
+This phase attempts to build the `install.do` target, if it exists.
+
+[]{#haredo-hook-haredoInstallTargets} Targets can be explicitly set by adding a string to the `haredoInstallTargets` list.
+
+[]{#haredo-hook-dontUseHaredoInstall} This behavior can be disabled by setting `dontUseHaredoInstall` to `true`.

doc/hooks/index.md

@@ -15,6 +15,7 @@ cmake.section.md
 gdk-pixbuf.section.md
 ghc.section.md
 gnome.section.md
+haredo.section.md
 installShellFiles.section.md
 libiconv.section.md
 libxml2.section.md