Clean up index headers

Author: reardonj

docs/datatypes/writer.md

@@ -125,9 +125,9 @@ type Writer[L, V] = WriterT[Id, L, V]
 
 So, all the [Operations](#operations) defined in the previous section
 are actually coming from the [WriterT
-datatype](writert.md)
+datatype](../monadtransformers/writert.md)
 
-Most of the [`WriterT`](writert.md) functions require a
+Most of the [`WriterT`](../monadtransformers/writert.md) functions require a
 [`Functor[F]`](../typeclasses/functor.md) or
 [`Monad[F]`](../typeclasses/monad.md)
 instance. However, Cats provides all the necessary instances for the

docs/guidelines.md

@@ -109,7 +109,7 @@ abstract class KleisliInstance1 {
 We can introduce new type classes for the sake of adding laws that don't apply to the parent type class, e.g. `CommutativeSemigroup` and
 `CommutativeArrow`.
 
-### Applicative instances for monad transformers</a>
+### Applicative instances for monad transformers
 
 We explicitly don't provide an instance of `Applicative` for e.g. `EitherT[F, String, *]` given an `Applicative[F]`.
 An attempt to construct one without a proper `Monad[F]` instance would be inconsistent in `ap` with the provided `Monad` instance

docs/imports.md

@@ -8,7 +8,7 @@ import cats.data._
 import cats.syntax.all._
 ```
 
-The `cats._` import brings in quite a few [type classes](typeclasses.md) (similar to interfaces) such as [Monad](typeclasses/monad.md), [Semigroup](typeclasses/semigroup.md), and [Foldable](typeclasses/foldable.md). Instead of the entire `cats` package, you can import only the types that you need, for example:
+The `cats._` import brings in quite a few [type classes](typeclasses/index.md) (similar to interfaces) such as [Monad](typeclasses/monad.md), [Semigroup](typeclasses/semigroup.md), and [Foldable](typeclasses/foldable.md). Instead of the entire `cats` package, you can import only the types that you need, for example:
 
 ```scala mdoc:reset:silent
 import cats.Monad

docs/index.md

@@ -65,7 +65,7 @@ We thankfully accept <a href="https://opencollective.com/typelevel/donate">one-t
 
 <script src="/cats/js/sponsors.js"></script>
 
-### Getting Started
+## Getting Started
 
 Cats is available for [Scala.js](http://www.scala-js.org/) and [Scala Native](https://www.scala-native.org/), as well as the standard JVM runtime.
 
@@ -130,7 +130,7 @@ into larger problems.
 If you are being harassed, please contact one of [us](#maintainers)
 immediately so that we can support you.
 
-### Binary compatibility and versioning
+## Binary Compatibility and Versioning
 
 After `1.0.0` release, we [decided](https://github.com/typelevel/cats/issues/1233)
 to use *MAJOR.MINOR.PATCH* [Semantic Versioning 2.0.0](http://semver.org/)
@@ -157,11 +157,11 @@ Any binary breaking changes will require a *MAJOR* version bump, which we will b
 cautious about. We will also consider using `organization` and package name for major
 versioning in the future. But that decision is yet to be made.
 
-### Adopters
+## Adopters
 
 A (non-exhaustive) list of companies that use Cats in production is featured on the [Adopters page]. Don't see yours? [You can add it in a PR!](https://github.com/typelevel/cats/edit/main/ADOPTERS.md) And if you can, consider [supporting us](https://opencollective.com/typelevel).
 
-### Maintainers
+## Maintainers
 
 The current maintainers (people who can merge pull requests) are:
 
@@ -194,7 +194,7 @@ wait for more). For typos, documentation improvements or minor build fix we
 relax this to a single sign-off. More detail in the [process document](https://github.com/typelevel/cats/blob/main/PROCESS.md).
 
 
-### Copyright and License
+## Copyright and License
 
 All code is available to you under the MIT license, available at
 http://opensource.org/licenses/mit-license.php and also in the

docs/monadtransformers/directory.conf

@@ -1,6 +1,6 @@
 laika.title = Monad Transformers
 laika.navigationOrder = [
-  monadtransformers.md
+  index.md
   contt.md
   eithert.md
   iort.md

docs/monadtransformers/monadtransformers.md renamed to docs/monadtransformers/index.md

@@ -202,7 +202,7 @@ If any of the checks fails, the resulting `EitherT` will contain a `Left` value.
 Otherwise, if all of the checks yield a `Right` (of course we mean a `Right` wrapped into an `EitherT`), then the final outcome will also contain `Right`.
 This is a fail-fast behavior: we're effectively stopping the `for` comprehension flow at the first `Left`-ish result.
 
-If you're instead looking for validation that accumulates the errors (e.g. when dealing with user-provided form data), [Validated](datatypes/validated.md) or the [Parallel](typeclasses/parallel.md) applicative functor for `Either` may be a good choice.
+If you're instead looking for validation that accumulates the errors (e.g. when dealing with user-provided form data), [Validated](../datatypes/validated.md) or the [Parallel](../typeclasses/parallel.md) applicative functor for `Either` may be a good choice.
 
 ## Pitfalls
 

docs/motivations.md

@@ -15,7 +15,7 @@ page](CONTRIBUTING.md) to find out ways to give us feedback.
 #### Modularity
 
 We are trying to make the library modular. It will have a tight
-core which will contain only the [type classes](typeclasses.md),
+core which will contain only the [type classes](typeclasses/index.md),
 the bare minimum of data structures that are needed to support
 them, and type class instances for those data structures and standard
 library types.

docs/typeclasses/directory.conf

@@ -1,6 +1,6 @@
 laika.title = Type Classes
 laika.navigationOrder = [
-  typeclasses.md
+  index.md
   alternative.md
   applicative.md
   applicativemonaderror.md

docs/typeclasses/typeclasses.md renamed to docs/typeclasses/index.md

@@ -1,6 +1,6 @@
 # Law testing
 
-[Laws](../typeclasses.md#laws) are an important part of cats.
+[Laws](../typeclasses/index.md#laws) are an important part of cats.
 Cats uses [discipline](https://github.com/typelevel/discipline) to define type class laws and
 the [ScalaCheck](https://github.com/rickynils/scalacheck) tests based on them.