Add doc comments for Unwrap, IsVariant

Prevents a linting issue from `missing_docs` on the derived functions

src/is_variant.rs

@@ -42,6 +42,9 @@ pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStre
             Fields::Unit => quote! {},
         };
         let func = quote! {
+            #[doc = "Returns `true` if this value is of type `"]
+            #[doc = stringify!(#variant_ident)]
+            #[doc = "`. Returns `false` otherwise"]
             pub fn #fn_name(&self) -> bool {
                 match self {
                     #enum_name ::#variant_ident #data_pattern => true,

src/unwrap.rs

@@ -81,6 +81,9 @@ pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStre
         };
         let func = quote! {
             #track_caller
+            #[doc = "Unwraps this value to the `"]
+            #[doc = stringify!(#variant_ident)]
+            #[doc = "` variant\n\nPanics if this value is of any other type"]
             pub fn #fn_name(self) -> #ret_type {
                 match self {
                     #enum_name ::#variant_ident #data_pattern => #ret_value,