Capitalize starts of footnotes

Author: ehuss

src/expressions/operator-expr.md

@@ -539,17 +539,17 @@ reference types and `mut` or `const` in pointer types.
 | [Function pointer]    | Integer               | Function pointer to address cast                      |
 | Closure [^no-capture] | Function pointer      | Closure to function pointer cast                      |
 
-[^meta-compat]: where `T` and `V` have compatible metadata:
+[^meta-compat]: Where `T` and `V` have compatible metadata:
       * `V: Sized`, or
       * Both slice metadata (`*[u16]` -> `*[u8]`, `*str` -> `*(u8, [u32])`), or
       * Both the same trait object metadata, modulo dropping auto traits (`*dyn Debug` -> `*(u16, dyn Debug)`, `*dyn Debug + Send` -> `*dyn Debug`)
           * **Note**: *adding* auto traits is only allowed if the principal trait has the auto trait as a super trait (given `trait T: Send {}`, `*dyn T` -> `*dyn T + Send` is valid, but `*dyn Debug` -> `*dyn Debug + Send` is not)
           * **Note**: Generics (including lifetimes) must match (`*dyn T<'a, A>` -> `*dyn T<'b, B>` requires `'a = 'b` and `A = B`)
 
-[^lessmut]: only when `m₁` is `mut` or `m₂` is `const`. Casting `mut` reference/pointer to
+[^lessmut]: Only when `m₁` is `mut` or `m₂` is `const`. Casting `mut` reference/pointer to
 `const` pointer is allowed.
 
-[^no-capture]: only closures that do not capture (close over) any local variables can be casted to function pointers.
+[^no-capture]: Only closures that do not capture (close over) any local variables can be casted to function pointers.
 
 ### Semantics