Update documenter, add minimal docs for labeled break

[Keno]

The primary purpose of this PR is to update documenter to enable doctests that use 1.14 syntax. To ensure everything is working, add some doctests that use labeled break.

Written by Claude.

[Keno]

@fingolfin the PDF build is failing with this documenter bump. Any ideas?

[fingolfin]

Unfortunately Documenter does not show the TeX log file. But I checked out this PR locally and did a make -C doc pdf. The resulting .log file ends with:

LaTeX Warning: `h' float specifier changed to `ht'.



[953]
! Illegal parameter number in definition of \Hy@tempa.
<to be read again> 
L
l.120057 \end{tabulary}
                     

Here is how much of LuaTeX's memory you used:
 55400 strings out of 475506
 6943765,4101490 words of node,token memory allocated
 38171 words of node memory still in use:
   346 hlist, 99 vlist, 126 rule, 199 disc, 102 local_par, 5 dir, 4 math, 1120 g
lue, 119 kern, 285 penalty, 13 unset, 2109 glyph, 2 align_record, 897 attribute,
 205 glue_spec, 897 attribute_list, 9 temp, 1 align_stack, 5 write, 25 pdf_start
_link, 25 pdf_end_link, 2 pdf_dest, 117 pdf_action, 63 pdf_colorstack nodes
   avail lists: 1:8,2:170501,3:100028,4:4751,5:23624,6:29668,7:595528,8:44,9:164
131,10:26,11:21817
 73829 multiletter control sequences out of 65536+600000
 104 fonts using 78444567 bytes
 115i,21n,132p,1753b,1813s stack positions out of 10000i,1000n,20000p,200000b,200000s
!  ==> Fatal error occurred, no output PDF file produced!

So it chokes at the end of the table. The table in question is from stdlib/LinearAlgebra-0eaade81fae264f9802df0e79b24ebc625f21305/docs/src/index.md:

| Type               | Description                                                                                                    |
|:------------------ |:-------------------------------------------------------------------------------------------------------------- |
| `BunchKaufman`     | Bunch-Kaufman factorization                                                                                    |
| `Cholesky`         | [Cholesky factorization](https://en.wikipedia.org/wiki/Cholesky_decomposition)                                 |
| `CholeskyPivoted`  | [Pivoted](https://en.wikipedia.org/wiki/Pivot_element) Cholesky factorization                                  |
| `LDLt`             | [LDL(T) factorization](https://en.wikipedia.org/wiki/Cholesky_decomposition#LDL_decomposition)                 |
| `LU`               | [LU factorization](https://en.wikipedia.org/wiki/LU_decomposition)                                             |
| `QR`               | [QR factorization](https://en.wikipedia.org/wiki/QR_decomposition)                                             |
| `QRCompactWY`      | Compact WY form of the QR factorization                                                                        |
| `QRPivoted`        | Pivoted [QR factorization](https://en.wikipedia.org/wiki/QR_decomposition)                                     |
| `LQ`               | [QR factorization](https://en.wikipedia.org/wiki/QR_decomposition) of `transpose(A)`                           |
| `Hessenberg`       | [Hessenberg decomposition](https://mathworld.wolfram.com/HessenbergDecomposition.html)                          |
| `Eigen`            | [Spectral decomposition](https://en.wikipedia.org/wiki/Eigendecomposition_of_a_matrix)                         |
| `GeneralizedEigen` | [Generalized spectral decomposition](https://en.wikipedia.org/wiki/Eigendecomposition_of_a_matrix#Generalized_eigenvalue_problem)                            |
| `SVD`              | [Singular value decomposition](https://en.wikipedia.org/wiki/Singular_value_decomposition)                     |
| `GeneralizedSVD`   | [Generalized SVD](https://en.wikipedia.org/wiki/Generalized_singular_value_decomposition#Higher_order_version) |
| `Schur`            | [Schur decomposition](https://en.wikipedia.org/wiki/Schur_decomposition)                                       |
| `GeneralizedSchur` | [Generalized Schur decomposition](https://en.wikipedia.org/wiki/Schur_decomposition#Generalized_Schur_decomposition) |

With some trial and error, it seems the # in one of the URL causes the problem. Grr: we do test building the Julia manual in Documenter's CI tests, but only the HTML version. I made JuliaDocs/Documenter.jl#2877 to also test building the PDF, and will track down the regression and work on a fix.

[fingolfin]

Correction: I'll do that after some sleep...