docs(users/Profpatsch): Add small README to most subdirs

Change-Id: I2912e32fe1b2d3d3aff7bafba809634ec4c9adb6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8470
Autosubmit: Profpatsch <mail@profpatsch.de>
Reviewed-by: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI

users/Profpatsch/my-prelude/README.md

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+# My Haskell Prelude
+
+Contains various modules I’ve found useful when writing Haskell.
+
+## Contents
+
+A short overview:
+
+### `MyPrelude.hs`
+
+A collection of re-exports and extra functions. This does *not* replace the `Prelude` module from `base`, but rather should be imported *in addition* to `Prelude`.
+
+Stuff like bad functions from prelude (partial stuff, or plain horrible stuff) are handled by a custom `.hlint` file, which you can find in [../.hlint.yaml]().
+
+The common style of haskell they try to enable is what I call “left-to-right Haskell”,
+where one mostly prefers forward-chaining operators like `&`/`<&>`/`>>=` to backwards operators like `$`/`<$>`/`<=<`. In addition, all transformation function should follow the scheme of `aToB` instead of `B.fromA`, e.g. `Text.unpack`/`Text.pack` -> `textToString`/`stringToText`. Includes a bunch of text conversion functions one needs all the time, in the same style.
+
+These have been battle-tested in a production codebase of ~30k lines of Haskell.
+
+### `Label.hs`
+
+A very useful collection of anonymous labbeled tuples and enums of size 2 and 3. Assumes GHC >9.2 for `RecordDotSyntax` support.
+
+### `Pretty.hs`
+
+Colorful multiline pretty-printing of Haskell values.
+
+### `Test.hs`
+
+A wrapper around `hspec` which produces colorful test diffs.
+
+### `Aeson.hs`
+
+Helpers around Json parsing.
+
+### `Data.Error.Tree`
+
+Collect errors (from [`Data.Error`](https://hackage.haskell.org/package/error-1.0.0.0/docs/Data-Error.html)) into a tree, then display them in a nested fashion. Super useful for e.g. collecting and displaying nested parsing errors.