Fix hover docs for self and boolean keywords (FuelLabs#4469)

## Description

Closes FuelLabs#3967
FuelLabs#3966


![image](https://user-images.githubusercontent.com/47993817/233210418-1a641c16-9448-4ae9-bb67-8e2ef09effcc.png)


![image](https://user-images.githubusercontent.com/47993817/233210467-77f6710e-5447-4910-9181-8d80baafbfc0.png)

## Checklist

- [x] I have linked to any relevant issues.
- [ ] I have commented my code, particularly in hard-to-understand
areas.
- [ ] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [x] I have added tests that prove my fix is effective or that my
feature works.
- [ ] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [x] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [x] I have requested a review from the relevant team or maintainers.

sway-lsp/src/capabilities/hover.rs

@@ -26,7 +26,10 @@ pub fn hover_data(
     let range = get_range_from_span(&ident.span());
 
     // check if our token is a keyword
-    if token.kind == SymbolKind::Keyword {
+    if matches!(
+        token.kind,
+        SymbolKind::BoolLiteral | SymbolKind::Keyword | SymbolKind::SelfKeyword
+    ) {
         let name = ident.as_str();
         let documentation = keyword_docs.get(name).unwrap();
         let prefix = format!("\n```sway\n{name}\n```\n\n---\n\n");

sway-lsp/tests/lib.rs

@@ -1609,6 +1609,53 @@ async fn hover_docs_with_code_examples() {
     let _ = lsp::hover_request(&mut service, &hover, &mut i).await;
 }
 
+#[tokio::test]
+async fn hover_docs_for_self_keywords() {
+    let (mut service, _) = LspService::new(Backend::new);
+    let uri = init_and_open(
+        &mut service,
+        test_fixtures_dir().join("completion/src/main.sw"),
+    )
+    .await;
+    let mut i = 0..;
+
+    let mut hover = HoverDocumentation {
+        req_uri: &uri,
+        req_line: 11,
+        req_char: 13,
+        documentation: "\n```sway\nself\n```\n\n---\n\n The receiver of a method, or the current module.\n\n `self` is used in two situations: referencing the current module and marking\n the receiver of a method.\n\n In paths, `self` can be used to refer to the current module, either in a\n [`use`] statement or in a path to access an element:\n\n ```sway\n use std::contract_id::{self, ContractId};\n ```\n\n Is functionally the same as:\n\n ```sway\n use std::contract_id;\n use std::contract_id::ContractId;\n ```\n\n `self` as the current receiver for a method allows to omit the parameter\n type most of the time. With the exception of this particularity, `self` is\n used much like any other parameter:\n\n ```sway\n struct Foo(u32);\n\n impl Foo {\n     // No `self`.\n     fn new() -> Self {\n         Self(0)\n     }\n\n     // Borrowing `self`.\n     fn value(&self) -> u32 {\n         self.0\n     }\n\n     // Updating `self` mutably.\n     fn clear(ref mut self) {\n         self.0 = 0\n     }\n }\n ```",
+    };
+
+    let _ = lsp::hover_request(&mut service, &hover, &mut i).await;
+    hover.req_char = 24;
+    hover.documentation = "```sway\nstruct MyStruct\n```\n---";
+    let _ = lsp::hover_request(&mut service, &hover, &mut i).await;
+}
+
+#[tokio::test]
+async fn hover_docs_for_boolean_keywords() {
+    let (mut service, _) = LspService::new(Backend::new);
+    let uri = init_and_open(
+        &mut service,
+        test_fixtures_dir().join("tokens/storage/src/main.sw"),
+    )
+    .await;
+    let mut i = 0..;
+
+    let mut hover = HoverDocumentation {
+        req_uri: &uri,
+        req_line: 13,
+        req_char: 36,
+        documentation: "\n```sway\nfalse\n```\n\n---\n\n A value of type [`bool`] representing logical **false**.\n\n `false` is the logical opposite of [`true`].\n\n See the documentation for [`true`] for more information.",
+    };
+
+    let _ = lsp::hover_request(&mut service, &hover, &mut i).await;
+    hover.req_line = 25;
+    hover.req_char = 27;
+    hover.documentation = "\n```sway\ntrue\n```\n\n---\n\n A value of type [`bool`] representing logical **true**.\n\n Logically `true` is not equal to [`false`].\n\n ## Control structures that check for **true**\n\n Several of Sway's control structures will check for a `bool` condition evaluating to **true**.\n\n   * The condition in an [`if`] expression must be of type `bool`.\n     Whenever that condition evaluates to **true**, the `if` expression takes\n     on the value of the first block. If however, the condition evaluates\n     to `false`, the expression takes on value of the `else` block if there is one.\n\n   * [`while`] is another control flow construct expecting a `bool`-typed condition.\n     As long as the condition evaluates to **true**, the `while` loop will continually\n     evaluate its associated block.\n\n   * [`match`] arms can have guard clauses on them.";
+    let _ = lsp::hover_request(&mut service, &hover, &mut i).await;
+}
+
 #[tokio::test]
 async fn rename() {
     let (mut service, _) = LspService::new(Backend::new);