Add disallowed_macros lint

src/docs/disallowed_macros.txt

@@ -0,0 +1,36 @@
+### What it does
+Denies the configured macros in clippy.toml
+
+Note: Even though this lint is warn-by-default, it will only trigger if
+macros are defined in the clippy.toml file.
+
+### Why is this bad?
+Some macros are undesirable in certain contexts, and it's beneficial to
+lint for them as needed.
+
+### Example
+An example clippy.toml configuration:
+```
+disallowed-macros = [
+    # Can use a string as the path of the disallowed macro.
+    "std::print",
+    # Can also use an inline table with a `path` key.
+    { path = "std::println" },
+    # When using an inline table, can add a `reason` for why the macro
+    # is disallowed.
+    { path = "serde::Serialize", reason = "no serializing" },
+]
+```
+```
+use serde::Serialize;
+
+// Example code where clippy issues a warning
+println!("warns");
+
+// The diagnostic will contain the message "no serializing"
+#[derive(Serialize)]
+struct Data {
+    name: String,
+    value: usize,
+}
+```