Add remind appendix to book search

extension/command/help.js

@@ -14,7 +14,7 @@ class HelpCommand extends Command {
             "~": `Prefix ${c.match("~")} to search external crate's docs`,
             "@": `Prefix ${c.match("@crate")} (${c.dim("e.g. @tokio")}) to search that crate's doc exclusively`,
             "#": `Prefix ${c.match("#")} to search builtin attributes`,
-            "%": `Prefix ${c.match("%")} to search Rust official book chapters`,
+            "%": `Prefix ${c.match("%")} to search Rust book chapters`,
             ">": `Prefix ${c.match(">")} to search Rust clippy lints`,
             "?": `Prefix ${c.match("?")} to search caniuse.rs`,
             "1.": `Input ${c.match("Rust version")} (${c.dim("e.g. 1.42.0")}) to open its release page`,

extension/main.js

@@ -377,7 +377,13 @@ function getPlatformOs() {
                 content: page.url,
                 description: `${[...parentTitles.map(t => c.escape(t)), c.match(c.escape(page.title))].join(" > ")} - ${c.dim(page.name)}`
             }
-        }
+        },
+        onAppend: () => {
+            return [{
+                content: ":book",
+                description: `Remind: ${c.dim("you can use")} :book ${c.dim("command to search all Rust books.")}`,
+            }];
+        },
     });
 
     const LINT_URL = "https://rust-lang.github.io/rust-clippy/master/";