Re-do the 30 minute intro

This was originally on my blog, so it's incredibly informal. Let's make
it better.
update jemalloc

This includes optimizations to the thread cache and support for
shrinking and expanding huge (>4M) allocations in-place.
Fixed iOS build (statics name lint)
rustdoc: make calls of markdown::render safer

Previously, external code might call `markdown::render()` without having
called `markdown::reset_headers()`, meaning the TLS key
`used_header_map` was unset.  Now `markdown::render()` ensures that
`used_header_map` is set by calling `reset_headers` if necessary.

Fix #17736
rustdoc: Correctly name lifetimes in bounds

Fix #16518
rustdoc: Support unboxed fn sugar in bounds
rustdoc: Remove dummy UnknownBound variant
auto merge of #17812 : thestinger/rust/jemalloc, r=alexcrichton

This includes optimizations to the thread cache and support for
shrinking and expanding huge (>4M) allocations in-place.
auto merge of #17814 : vhbit/rust/ios-build-fix, r=huonw
rustdoc: Include lifetimes in re-exported bounds

Fix #17818
Add example to doc for `slice::ImmutableSlice::binary_search`.

Fix #17817.
syntax: Parse outer attributes in quote_method!

Fixes #17782.
auto merge of #17796 : tomjakubowski/rust/rustdoc-ice-17736, r=alexcrichton

Previously, external code might call `markdown::render()` without having
called `markdown::reset_headers()`, meaning the TLS key
`used_header_map` was unset.  Now `markdown::render()` ensures that
`used_header_map` is set by calling `reset_headers` if necessary.

Fix #17736
auto merge of #17798 : tomjakubowski/rust/rustdoc-fix-bounds, r=alexcrichton

This PR adds support in rustdoc for properly naming lifetimes in bounds, instead of just showing `'static` for everything. It also adds support for unboxed function sugar bounds, which were also previously rendered as `'static`.
Update COPYRIGHT to better reflect the current repo
auto merge of #17692 : brson/rust/copywut, r=alexcrichton
auto merge of #17820 : pnkfelix/rust/fsk-improve-binary_search-doc2, r=alexcrichton

Add example to doc for `slice::ImmutableSlice::binary_search`.

Fix #17817.
doc: Update output of `rustc --version`
Remove core::any::AnyPrivate

[Previously](https://github.com/rust-lang/rust/commit/e5da6a71a6a0b46dd3630fc8326e6d5906a1fde6),
the `Any` trait was split into a private portion and an (empty) public
portion, in order to hide the implementation strategy used for
downcasting. However, the [new
rules](https://github.com/rust-lang/rust/commit/e9ad12c0cae5c43ada6641c7dc840a0fbe5010a2)
for privacy forbid `AnyPrivate` from actually being private.

This patch thus reverts the introduction of `AnyPrivate`.

Although this is unlikely to break any real code, it removes a public
trait and is therefore a:

[breaking-change]
Revise DST test to not require duplicate errors.