style: fix enum variants formatting to follow linting convention

Add missing line breaks between enum variants in CloudInitContextError
and CommandError enums to follow the linting guide convention that
requires blank lines between error enum variants for better readability.

Files changed:
- src/infrastructure/template/wrappers/tofu/lxd/cloud_init/context.rs
- src/shared/executor.rs
- docs/linting.md (documentation example fix)

Author: josecelano

docs/linting.md

@@ -65,6 +65,7 @@ Error enum variants should be separated by blank lines for better readability.
 pub enum CloudInitContextError {
     #[error("SSH public key is required but not provided")]
     MissingSshPublicKey,
+    
     #[error("Failed to read SSH public key from file: {0}")]
     SshPublicKeyReadError(String),
 }

src/infrastructure/template/wrappers/tofu/lxd/cloud_init/context.rs

@@ -15,10 +15,13 @@ use crate::shared::Username;
 pub enum CloudInitContextError {
     #[error("SSH public key is required but not provided")]
     MissingSshPublicKey,
+
     #[error("Username is required but not provided")]
     MissingUsername,
+
     #[error("Invalid username: {0}")]
     InvalidUsername(String),
+
     #[error("Failed to read SSH public key from file: {0}")]
     SshPublicKeyReadError(String),
 }

src/shared/executor.rs

@@ -26,6 +26,7 @@ pub enum CommandError {
         #[source]
         source: std::io::Error,
     },
+
     /// The command was started but exited with a non-zero status code
     #[error(
         "Command '{command}' failed with exit code {exit_code}\nStdout: {stdout}\nStderr: {stderr}"