more direnv-related styling of README

Author: bobular

README.adoc

@@ -25,13 +25,13 @@ export YARN_NPM_MINIMAL_AGE_GATE=10080
 - `YARN_IGNORE_PATH=true`: The repository includes a bundled Yarn 3.3.1 binary for legacy deployment servers. This tells Yarn 4 to ignore it and use corepack instead.
 - `YARN_NPM_MINIMAL_AGE_GATE=10080`: Protects against supply chain attacks by requiring NPM packages to be at least 7 days old before installation (Yarn 4+ feature).
 
-.Setting these variables - two options:
-****
-==== Option A: Global shell configuration (simple)
+==== Setting these variables - two options:
+
+*Option A: Global shell configuration (simple)*
 
 Add the variables to your shell profile (`.bashrc`, `.zshrc`, etc.) as shown above. These will apply to all Yarn projects on your system.
 
-==== Option B: Per-repository with direnv (recommended)
+*Option B: Per-repository with direnv (recommended)*
 
 Use https://direnv.net/[direnv] to automatically set these variables only when working in this repository:
 
@@ -60,7 +60,6 @@ direnv allow
 ----
 
 The environment variables will now be set automatically whenever you enter this repository directory, and unset when you leave.
-****
 
 === Setup with Volta (Recommended)