doc: initial design proposal

.prettierignore

@@ -0,0 +1,9 @@
+# We are using https://standardjs.com coding style. It is unfortunately incompatible with Prettier;
+# see https://github.com/standard/standard/issues/996 and the linked issues.
+# Standard does not handle Markdown files though, so we want to use Prettier formatting.
+# The goal of the configuration below is to configure Prettier to lint only Markdown files.
+**/*.*
+!**/*.md
+
+# Let's keep LICENSE.md in the same formatting as we use in other PL repositories
+LICENSE.md

.prettierrc.yaml

@@ -0,0 +1,2 @@
+printWidth: 80
+proseWrap: always

README.md

@@ -1,3 +1,5 @@
 # piece-indexer
 
 A lightweight IPNI node mapping Filecoin PieceCID → payload block CID.
+
+- [Design doc](./docs/design.md)