Add new errors from polykinds branch (#300)

Author: natefaubion

errors/CycleInKindDeclaration.md

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+# `CycleInKindDeclaration` Error
+
+## Cause
+
+A top-level kind signature is declared in a way that would incur a dependency on itself.
+
+## Fix
+
+- A kind signature cannot depend on itself.
+- Check the kind signature for any types mentioned in the kind signature.

errors/InternalCompilerError.md

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+# `InternalCompilerError` Error
+
+## Cause
+
+An internal compiler invariant was violated, aborting compilation. This is a
+defect in the compiler.
+
+## Fix
+
+- Report the error to [the PureScript compiler repo](https://github.com/purescript/purescript).

errors/OrphanKindDeclaration.md

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+# `OrphanKindDeclaration` Error
+
+## Example
+
+```purescript
+data Proxy :: forall k. k -> Type
+```
+
+## Cause
+
+A top-level kind signature is provided but not immediately followed by it's declaration.
+
+## Fix
+
+- Check that you've provided the appropriate `data`, `newtype`, `type`, or `class` declaration.
+- Check that the keywords match.

errors/QuantificationCheckFailureInKind.md

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+# `QuantificationCheckFailureInKind` Error
+
+## Cause
+
+This error occurs when implicitly generalizing the kind of a `forall`
+quantified type variable would result in an ill-scoped generalization. The
+compiler always orders implicitly generalized kind variables first within a
+`forall` quantifier. It's possible to introduce a dependency on an explicit
+type variable in an inferred kind such that generalizing that kind would
+place it out of the scope of its dependency.
+
+## Fix
+
+- Generalize and order the kind explicitly

errors/QuantificationCheckFailureInType.md

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+# `QuantificationCheckFailureInType` Error
+
+## Example
+
+```purescript
+data Proxy :: forall k. k -> Type
+data Proxy a = Proxy
+
+type SomeProxy = forall a. Proxy a
+```
+
+## Cause
+
+This error occurs when the compiler tries to implicitly generalize a kind but
+there are multiple ways in which it could be quantified. This most often
+happens in the right-hand-side of type synonyms. In the above example, what
+is the kind of the type variable `a`?
+
+```purescript
+type SomeProxy = forall (a :: ???). Proxy a
+```
+
+We know that it could potentially be anything per the kind signature of
+`Proxy`, but how should it be quantified?
+
+```purescript
+-- Quantifying in the forall.
+type SomeProxy = forall k (a :: k). Proxy a
+
+-- Quantifying in a kind signature
+type SomeProxy :: forall k. Type
+type SomeProxy = forall (a :: k). Proxy a
+
+-- Quantify explicitly with an argument to the synonym
+type SomeProxy k = forall (a :: k). Proxy a
+```
+
+The only places the compiler considers unambiguous are within top-level type
+and kind signatures.
+
+## Fix
+
+- Explicitly quantify the kind in the way most appropriate for your use case.

errors/UnsupportedTypeInKind.md

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+# `UnsupportedTypeInKind` Error
+
+## Example
+
+```purescript
+foreign import data Bad :: SomeConstraint => Type
+```
+
+## Cause
+
+Not all types are valid in a kind signature. Particularly constraint arrows
+(`=>`) are disallowed since they only make sense for term-level constraint
+dependencies.
+
+## Fix
+
+- Only use types that are valid in kinds.

errors/VisibleQuantificationCheckFailureInType.md

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+# `VisibleQuantificationCheckFailureInType` Error
+
+## Cause
+
+Kinds are annotated in such a way that they require a visible dependent quantifier.
+
+## Fix
+
+- Visible dependent quantification is not supported.

errors/WarningParsingModule.md

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+# `WarningParsingModule` Warning
+
+## Cause
+
+The language parser found deprecated (but still valid) syntax. Your program
+still compiles fine, but will be rejected in the future.
+
+## Fix
+
+- Follow the instructions in the warning, or apply the suggested fix
+  automatically if one is provided.