Nu Shell Development Updates

# This week in Nu #39 - filalex added `--regex` to the `parse` command ([#1863](https://github.com/nushell/nushell/pull/1863)) - mhmdanas began abstracting code blocks in the book so languages could share examples ([#99](https://github.com/nushell/book/pull/99)) - fdnced improved the row auto-rotation heuristic ([#1861](https://github.com/nushell/nushell/pull/1863)), added instructions for pipenv to nu_jupyter ([#1](https://github.com/nushell/nu_jupyter/pull/1)) - zombie110year translated the first few chapters of the book to simplified Chinese ([#97](https://github.com/nushell/book/pull/97)) - AaronC81 improved completions for paths with spaces ([#1858](https://github.com/nushell/nushell/pull/1863)), bumped the minimum Rust version in the README ([#1851](https://github.com/nushell/nushell/pull/1851)) - ryespeg finished documenting the comparisons of Nu with a set of functional and imperative languages ([#93](https://github.com/nushell/book/pull/93)) - jonathandturner added some notes on Nu's current progress to the README ([#1854](https://github.com/nushell/nushell/pull/1854)), added string interpolation (eg ls | echo `{{name}} is a path`) ([#1849](https://github.com/nushell/nushell/pull/1849)), updated `format` to accept variables also ([#1842](https://github.com/nushell/nushell/pull/1842)), moved error reporting from language-reporting to codespan ([#1825](https://github.com/nushell/nushell/pull/1825)), fixed a bug where starship wasn't getting sent the pwd ([#1822](https://github.com/nushell/nushell/pull/1822)), bumped dependencies ([#1809](https://github.com/nushell/nushell/pull/1809)), moved plugins to use modern it-expansion ([#1807](https://github.com/nushell/nushell/pull/1807)), added support for `$(block)` form for argument command invocation ([#1801](https://github.com/nushell/nushell/pull/1801)) - JosephTLyons added a count to `histogram` ([#1853](https://github.com/nushell/nushell/pull/1853)), made `to json` pretty print indentation configurable ([#1818](https://github.com/nushell/nushell/pull/1818)), added pretty printing to `to json` ([#1812](https://github.com/nushell/nushell/pull/1812)), cleaned up a blog post ([#23](https://github.com/nushell/blog/pull/23))

This week's updates to the Nu shell include adding regex to the parse command, abstracting code blocks in the book, improving row auto-rotation, translating the book to simplified Chinese, improving path completions, documenting Nu's comparisons with other languages, adding string interpolation, updating the format command, moving error reporting, fixing a starship bug, updating dependencies, and adding support for argument command invocation. Other changes include adding a count to histogram, making to json pretty print indentation configurable, and cleaning up a blog post.