And short descriptions to all solana-program modules and macros. (#24128)

* And short descriptions to all solana-program modules and macros.

Also fill out some of the docs within these modules.

* Update sdk/program/src/lib.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/sanitize.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/pubkey.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

* Update hash module docs

* Make solana-program crate docs match Pubkey docs

* Update sdk/program/src/program_memory.rs

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

interface/src/instruction.rs

@@ -1,3 +1,7 @@
+//! Instructions and constructors for the system program.
+//!
+//! The system program ID is defined in [`system_program`].
+
 #[allow(deprecated)]
 use {
     crate::{

interface/src/lib.rs

@@ -1 +1,5 @@
+//! The [system native program][np].
+//!
+//! [np]: https://docs.solana.com/developing/runtime-facilities/sysvars#stakehistory
+
 crate::declare_id!("11111111111111111111111111111111");