improve documentation of some functions and more readme work

src/entries.rs

@@ -1,11 +1,18 @@
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 
+/// Declares a boot entry to display in the boot menu.
+///
+/// Entries are the user-facing concept of Sprout, making it possible
+/// to run a set of actions with a specific context.
 #[derive(Serialize, Deserialize, Default, Clone)]
 pub struct EntryDeclaration {
+    /// The title of the entry which will be display in the boot menu.
     pub title: String,
+    /// The actions to run when the entry is selected.
     #[serde(default)]
     pub actions: Vec<String>,
+    /// The values to insert into the context when the entry is selected.
     #[serde(default)]
     pub values: BTreeMap<String, String>,
 }