Move files to ruby subfolder

ruby/doc/HOWTO.md

@@ -0,0 +1,47 @@
+# Developer information
+
+This document contains information about common development tasks.
+
+## Building the tools from source
+
+[Install Rust](https://www.rust-lang.org/tools/install), then run:
+
+```bash
+cargo build --release
+```
+
+## Generating the database schema and QL library
+
+The generated `ql/lib/ruby.dbscheme` and `ql/lib/codeql/ruby/ast/internal/TreeSitter.qll` files are included in the repository, but they can be re-generated as follows:
+
+```bash
+# Run the generator
+cargo run --release -p ruby-generator -- --dbscheme ql/lib/ruby.dbscheme --library ql/lib/codeql/ruby/ast/internal/TreeSitter.qll
+# Then auto-format the QL library
+codeql query format -i ql/lib/codeql/ruby/ast/internal/TreeSitter.qll
+```
+
+## Building a CodeQL database for a Ruby program
+
+First, get an extractor pack. There are two options:
+
+1. Either download the latest `codeql-ruby-pack` from Actions and unzip it twice, or
+2. Run `scripts/create-extractor-pack.sh` (Linux/Mac) or `scripts\create-extractor-pack.ps1` (Windows PowerShell) and the pack will be created in the `extractor-pack` directory.
+
+Then run
+
+```bash
+codeql database create <database-path> -l ruby -s <project-source-path> --search-path <extractor-pack-path>
+```
+
+## Running qltests
+
+Run
+
+```bash
+codeql test run <test-path> --search-path <repository-root-path>
+```
+
+## Writing database upgrade scripts
+
+See [this guide](prepare-db-upgrade.md).