Release notes for 0.85.0 (#1046)

* Create 2023-09-19-nushell_0_85_0.md

* add blurb about uutils/coreutils integration

* add the full template for the release notes

this commit also breaks the paragraph about uutils into multiple lines.

* add the raw table of contributions

* remove the bump / dependabot commits

* isolate the fixes

* more updates

* put all the PRs in proto sections

* move uutils PR to the correct section

* add TODOs and start completing some sections

* add the raw list of breaking changes

* add the full changelog

* write the "bug fixes" section

* fix a section title

* write the "documentation" section

* write the "making nushell better" section

this commit removes
| author        | description                                                | url                                                     |
| ------------- | ---------------------------------------------------------- | ------------------------------------------------------- |
| @kubouch      | Add NU_VERSION environment variable on startup             | [#10177](nushell/nushell#10177) |
| @mastermach50 | changed default env file to use $nu.home_path to find home | [#10192](nushell/nushell#10192) |
| @amtoine      | support tab completion cycling                             | [#10199](nushell/nushell#10199) |

because i'm not sure they are as interesting as the conditional sourcing
and the accessibility with screen reader friendly errors.

* write the "help with tests" section

* write the "changes to commands" section

* format and compact tables in the source

* write the "table themes" section

* write the `echo` section

* write the "python operators removal" section

* update the full changelog

* add proper uutils blog link

* Adds a note about mimalloc being default now (#1063)

* notes about history isolation changes

Co-authored-by: Hofer-Julian <30049909+Hofer-Julian@users.noreply.github.com>

* type-o in sourcing and using

* `float` instead of `decimal` (#1064)

* `float` instead of `decimal`

* fix oopsie

* Breaking change markers

* Has nothing to do with pure documentation

* Add new commands section

* Deprecation section/ link new commands

* Fix `from` commands in the STD

* Fix subcommand std imports

* Mention removal of deprecated `--string`

* Refactor const section (#1068)

* Update 2023-09-19-nushell_0_85_0.md

Move code to code block

* add link to uutils blog post

* Small formulation tweaks to breaking changes

* cleanup dmatos part

* change link to our blogpost

* Add excerpt

* Excerpt in metadata

* Fix emphasis

---------

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>
Co-authored-by: amtoine <stevan.antoine@gmail.com>
Co-authored-by: Filip Andersson <17986183+FilipAndersson245@users.noreply.github.com>
Co-authored-by: Hofer-Julian <30049909+Hofer-Julian@users.noreply.github.com>
Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>