chore: add README notice for Firefox reviewers

README.md

@@ -1,3 +1,44 @@
+NOTICE FOR FIREFOX ADD-ON REVIEWERS
+===================================
+
+This is the monorepo which contains the source code for Namada Extension.
+
+Source code
+-----------
+The main extension source code is located in `apps/extension/src`. We also use
+several local packages; their source is in:
+
+  - `packages/chains/src`
+  - `packages/components/src`
+  - `packages/hooks/src`
+  - `packages/sdk/src`
+  - `packages/storage/src`
+  - `packages/types/src`
+  - `packages/utils/src`
+  - `packages/shared/lib` (shared package Rust code compiled to WebAssembly)
+  - `packages/shared/src` (shared package TypeScript glue code)
+  - `packages/crypto/lib` (crypto package Rust code compiled to WebAssembly)
+  - `packages/crypto/src` (crypto package TypeScript glue code)
+
+Build instructions
+------------------
+These instructions should work for the default reviewer build environment.
+
+    sudo apt install protobuf-compiler build-essential
+    curl https://sh.rustup.rs -sSf | sh
+    npm install -g yarn
+    export PUPPETEER_SKIP_DOWNLOAD=true
+    yarn
+    cd apps/extension
+    yarn wasm:build
+    yarn build:firefox
+
+The resulting extension is the ZIP file in `apps/extension/build/firefox`.
+
+---
+
+(The following are the usual contents of the README.)
+
 <h1> namada-interface</h1>
 
 <div style="width: 100%; display: flex; justify-content: center; margin-bottom: 32px;">