(fix) Default rustfmt to the 2021 edition

(feat) docgen can now build docs from an external zq2 (so we can run a network and get docs at the same time)
(fix) Wording changes for changes.md

docgen/rustfmt.toml

@@ -0,0 +1 @@
+edition="2021"

docgen/src/main.rs

@@ -23,12 +23,9 @@ async fn main() -> Result<()> {
     let here = String::from(&args[1]);
 
     // Set NO_CHECKOUT to skip the checkout steps - this allows you to do debugging with symlinks or similar.
-    let checkout = std::env::var("NO_CHECKOUT").is_err();
+    let mut checkout = std::env::var("NO_CHECKOUT").is_err();
 
     // Find the zq2 versions that we need to collect.
-
-    println!("here = {here}");
-
     let root_path = PathBuf::from(&here);
     let versions: Zq2Spec =
         serde_yaml::from_str(&fs::read_to_string(format!("{}/zq2_spec.yaml", here))?)?;
@@ -45,8 +42,20 @@ async fn main() -> Result<()> {
             Some(ref val) => val.to_string(),
         };
         println!("Compiling zq2 version {name}");
-        let cache_dir: PathBuf = root_path.clone().join("cache");
-        let zq2_checkout_dir: PathBuf = cache_dir.clone().join("zq2");
+        let mut cache_dir: Option<PathBuf> = Some(root_path.clone().join("cache"));
+        let mut zq2_checkout_dir: PathBuf;
+        if let Ok(val) = std::env::var("USE_ZQ2_FROM") {
+            checkout = false;
+            cache_dir = None;
+            zq2_checkout_dir = PathBuf::from(val);
+        } else if let Some(val) = &cache_dir {
+            zq2_checkout_dir = val.clone().join("zq2");
+        } else {
+            return Err(anyhow!(
+                "No zq2 specified - no cache dir and USE_ZQ2_FROM is not specified"
+            ));
+        }
+
         let id_prefix = format!("Versions/{name}");
         let target_dir = root_path.clone().join("zq2").join("docs");
         let target_dir_str = target_dir
@@ -67,11 +76,11 @@ async fn main() -> Result<()> {
                     .run_logged()
                     .await?
                     .success_or("Cannot run git fetch")?
-            } else {
+            } else if let Some(val) = &cache_dir {
                 // Clone
                 CommandBuilder::new()
                     .cmd("git", &["clone", "https://github.com/zilliqa/zq2"])
-                    .current_dir(&cache_dir.clone())?
+                    .current_dir(&val.clone())?
                     .run_logged()
                     .await?
                     .success_or("Cannot run git clone")?

zq2/docs/changes.md

@@ -14,6 +14,11 @@ There are a number of differences between Zilliqa 1.0 and Zilliqa 2.0 that you s
 - Zilliqa 2.0 has a much faster block time (there is typically a hardwired minimum of 1s/block); dApp operators will need to make sure that where they use block number as a proxy for a timestamp, they allow sufficient blocks for users to react.
 - Zilliqa 2 upgrades are seamless and relatively quick; you don't need to redownload persistence and there is an auto-upgrader you can run if you wish which will run the newer version of zq2 and cut over when ready. We hope this will enable us to eliminate upgrade downtime and to make more frequent bug fixes.
 
+## API differences
+
+- There are no DS epochs any longer (though some are faked to allow existing applications that retrieve the current DS epoch to work), so the transaction pool is no longer cleared at the start of a DS epoch.
+- `GetTransactionStatus` no longer depends on an off-chain transaction store, and therefore now works for any transaction.
+
 ## Continuity
 
 There are also a number of things that have not changed: