shlvl docs for default symbol are inconsistent with code

[sersorrel]

the shlvl module defaults to two trailing spaces after the up-down arrow symbol:

starship/src/configs/shlvl.rs

Line 19 in 0be9ffc

symbol: "↕️ ", // extra space for emoji

but in the docs, symbol is listed with only one trailing space:

starship/docs/config/README.md

Line 2140 in 0f483fa

| `symbol` | `"↕️ "` | The symbol used to represent the SHLVL. |

imo the default should be to have only one trailing space, like other modules:

starship/src/configs/rust.rs

Line 17 in 0f483fa

symbol: "🦀 ",

but as long as the docs and code match i'm happy with either.

[andytom]

If I remember correctly the reason some modules have two training spaces is to work around some issues with double width emojis, so I believe the docs should be updated.

[kirktrue]

There do seem to be two spaces in the actual markup source for symbol under SHLVL's configuration options. When the README.md is rendered on GitHub, though, it is only rendering a single space.