Add aliases for python and Java collections

`append` sounds strange because Rust already has append and it does
something different. The reason I added it is one of my friends knew
from python that it added a single element to the end of an array. When
they started learning Rust, rather than looking for pop(), they wrote
something like

```rust
my_vec.append(&mut vec![x]);
```

which is clearly not ideal. Hopefully this would have pointed them in
the right direction.

Author: jyn514

library/alloc/src/collections/btree/map.rs

@@ -139,6 +139,9 @@ pub(super) const MIN_LEN: usize = node::MIN_LEN_AFTER_SPLIT;
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "BTreeMap")]
+#[doc(alias = "associative array")]
+#[doc(alias = "dict")]
+#[doc(alias = "map")]
 pub struct BTreeMap<K, V> {
     root: Option<Root<K, V>>,
     length: usize,

library/alloc/src/collections/btree/set.rs

@@ -62,6 +62,7 @@ use super::Recover;
 #[derive(Hash, PartialEq, Eq, Ord, PartialOrd)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "BTreeSet")]
+#[doc(alias = "set")]
 pub struct BTreeSet<T> {
     map: BTreeMap<T, ()>,
 }

library/alloc/src/vec/mod.rs

@@ -373,6 +373,7 @@ mod spec_extend;
 /// [`&`]: ../../std/primitive.reference.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "vec_type")]
+#[doc(alias = "list")]
 pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
     buf: RawVec<T, A>,
     len: usize,

library/std/src/collections/hash/map.rs

@@ -200,6 +200,9 @@ use crate::sys;
 
 #[cfg_attr(not(test), rustc_diagnostic_item = "hashmap_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[doc(alias = "associative array")]
+#[doc(alias = "dict")]
+#[doc(alias = "map")]
 pub struct HashMap<K, V, S = RandomState> {
     base: base::HashMap<K, V, S>,
 }

library/std/src/collections/hash/set.rs

@@ -110,6 +110,7 @@ use super::map::{map_try_reserve_error, RandomState};
 /// [`Cell`]: crate::cell::Cell
 #[cfg_attr(not(test), rustc_diagnostic_item = "hashset_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[doc(alias = "set")]
 pub struct HashSet<T, S = RandomState> {
     base: base::HashSet<T, S>,
 }