incorporate feedback

README.md

@@ -60,6 +60,11 @@ following to the macro to exclude it from `no-entrypoint` builds.
 #[cfg(not(feature = "no-entrypoint"))]
 ```
 
+#### Use as an indicator for the deployed code version
+
+In order to simplify access to the source code we recommend to include the commit hash as `source_revision` or the release tag as `source_release`.
+You can use the `option_env!` macro to automatically configure values passed to the `security_txt!` macro from the build process envioronment.
+
 ### Example
 
 ```rust
@@ -74,6 +79,8 @@ security_txt! {
     // Optional Fields
     preferred_languages: "en,de",
     source_code: "https://github.com/example/example",
+    source_revision: option_env!("GITHUB_SHA").unwrap().into(),
+    source_release: option_env!("GITHUB_REF_NAME").unwrap().into(),
     encryption: "
 -----BEGIN PGP PUBLIC KEY BLOCK-----
 Comment: Alice's OpenPGP certificate

security-txt/src/parser.rs

@@ -181,12 +181,8 @@ pub fn parse(mut data: &[u8]) -> Result<SecurityTxt, SecurityTxtError> {
         .remove("project_url")
         .ok_or_else(|| SecurityTxtError::MissingField("project_url".to_string()))?;
     let source_code = attributes.remove("source_code");
-    let source_release = attributes
-        .remove("source_release")
-        .or(option_env!("GITHUB_REF_NAME").map(|s| s.into()));
-    let source_revision = attributes
-        .remove("source_revision")
-        .or(option_env!("GITHUB_SHA").map(|s| s.into()));
+    let source_release = attributes.remove("source_release");
+    let source_revision = attributes.remove("source_revision");
     let expiry = attributes.remove("expiry");
     let preferred_languages = attributes
         .remove("preferred_languages")