message: doc: improve start of readme
diff: -Mesh: A compacting malloc(3) implementation
  -===========================================
  +Mesh: Compacting Memory Management for C, C++, and Rust
  +=======================================================
  Mesh is a drop in replacement for
  -[malloc(3)](http://man7.org/linux/man-pages/man3/malloc.3.html) that compacts the heap of C and C++ programs without rewriting application pointers.
  +[malloc(3)](http://man7.org/linux/man-pages/man3/malloc.3.html) that
  +compacts the heap without rewriting application pointers.
  +
  +Mesh runs on Linux; macOS support should be considered alpha-quality,
  +and Windows is a work-in-progress.
  +
  +Mesh has a standard C++ build process, and has no runtime dependencies
  +other than libc-related libs:
  +
  +```
  +$ git clone --recurse-submodules https://github.com/plasma-umass/mesh
  +$ cd mesh
  +$ ./configure; make; sudo make install
  +# example: run git with mesh as its allocator:
  +$ LD_PRELOAD=libmesh.so git status
  +```
  +
  +More docs coming soon, but please open up an issue if you have questions (or issues)!
  +
  Implementation Overview
  -----------------------
  @@ -33,10 +51,3 @@ DEFINITIONS
  particular size of objects (size class).
  - [**MeshingHeap**](src/include/meshingheap.h): A collection of miniheaps for a particular size
  class, including a _current_ MiniHeap that we are allocating out of.
  -
  -BUILDING
  ---------
  -
  -```
  -$ git submodule update --init; ./configure; make
  -```
  