doc/features.md: fix table formatting

VSC interprets a single `|` as continuing a table, rustdoc doesn't

Author: MaulingMonkey

doc/features.md

@@ -7,17 +7,17 @@ Cargo features of the [`ialloc`](crate) crate.
 | `"panicy-bounds"`     | APIs that panic on out of bounds indicies     |
 | `"panicy-memory"`     | APIs that panic when out of memory            |
 | (always)              | APIs that try to panic on undefined behavior  |
-|
+| |
 |                       | **Dependencies**
 | `"alloc"`             | [`alloc`] crate support (rust standard library) |
 | `"std"`               | [`std`] crate support (rust standard library) |
 | `"msvc"`              | MSVC-specific library support                 | <code>[target_env](https://doc.rust-lang.org/reference/conditional-compilation.html#target_env) = `"msvc"`</code>
 | `"win32"`             | Windows-specific allocators                   | <code>[target_os](https://doc.rust-lang.org/reference/conditional-compilation.html#target_os) = `"windows"`</code>
-|
+| |
 |                       | **Language Standards**
 | `"c89"`               | C89 standard library support                  | [`cc`](https://github.com/rust-lang/cc-rs) finds a C89+ compatible compiler
 | `"c11"`               | C11 standard library support                  | [`cc`](https://github.com/rust-lang/cc-rs) finds a C11+ compatible compiler
 | `"c23"`               | C23 standard library support                  | [`cc`](https://github.com/rust-lang/cc-rs) finds a C23+ compatible compiler
-|
+| |
 | `"c++98"`             | C++98 standard library support                | [`cc`](https://github.com/rust-lang/cc-rs) finds a C++98+ compatible compiler
 | `"c++17"`             | C++17 standard library support                | [`cc`](https://github.com/rust-lang/cc-rs) finds a C++17+ compatible compiler