Include more information in readme

README.md

@@ -17,6 +17,67 @@ anyhow = "=1.0.0-alpha.1"
 
 <br>
 
+## Details
+
+- Use `Result<T, anyhow::Error>`, or equivalently `anyhow::Result<T>`, as the
+  return type of any fallible function.
+
+  Within the function, use `?` to easily propagate any error that implements the
+  `std::error::Error` trait.
+
+  ```rust
+  use anyhow::Result;
+
+  fn get_cluster_info() -> Result<ClusterMap> {
+      let config = std::fs::read_to_string("cluster.json")?;
+      let map: ClusterMap = serde_json::from_str(&config)?;
+      Ok(map)
+  }
+  ```
+
+- Attach context to help the person troubleshooting the error understand where
+  things went wrong. A low-level error like "No such file or directory" can be
+  annoying to debug without more context about what higher level step the
+  application was in the middle of.
+
+  ```rust
+  use anyhow::{Context, Result};
+
+  fn main() -> Result<()> {
+      ...
+      it.detach().context("failed to detach the important thing")?;
+
+      let content = std::fs::read(path)
+          .with_context(|| format!("failed to read instrs from {}", path))?;
+      ...
+  }
+  ```
+
+  ```console
+  Error: failed to read instrs from ./path/to/instrs.jsox
+
+  caused by:
+      0: No such file or directory (os error 2)
+  ```
+
+- Downcasting is supported and can be by value, by shared reference, or by
+  mutable reference as needed.
+
+  ```rust
+  // If the error was caused by redaction, then return a
+  // tombstone instead of the content.
+  match root_cause.downcast_ref::<DataStoreError>() {
+      Some(DataStoreError::Censored(_)) => Ok(Poll::Ready(REDACTED_CONTENT)),
+      None => Err(error),
+  }
+  ```
+
+- A backtrace is captured and printed with the error if the underlying error
+  type does not already provide its own. In order to see backtraces, the
+  `RUST_LIB_BACKTRACE=1` environment variable must be defined.
+
+<br>
+
 ## Acknowledgements
 
 The implementation of the `anyhow::Error` type is identical to