docs: More docs and improvements of existing docs

- Tried not to leave a single public function undocumented, though did not double-document public function with obvious names
- Remove all mentions of the strategy selector in favour of the strategy registry (to avoid confusion)

src/encoding/swap_encoder.rs

@@ -3,17 +3,23 @@ use crate::encoding::{
     models::{EncodingContext, Swap},
 };
 
-/// This trait must be implemented in order to encode a swap for a specific protocol.
+/// This trait must be implemented in order to encode a single swap for a specific protocol.
 pub trait SwapEncoder: Sync + Send {
     fn new(executor_address: String) -> Self
     where
         Self: Sized;
+
+    /// Encodes a swap and its relevant context information into call data for a specific protocol.
     fn encode_swap(
         &self,
         swap: Swap,
         encoding_context: EncodingContext,
     ) -> Result<Vec<u8>, EncodingError>;
+
+    /// The address of the executor that will be used to swap through a specific protocol.
     fn executor_address(&self) -> &str;
+
+    /// The selector of the executor function that will be called in order to perform a swap.
     fn executor_selector(&self) -> &str;
 
     /// Clones the swap encoder as a trait object.