Too few backticks for a couple of in-line code elements in docs

A very minor issue whose first occurrence had me stumped for a bit: In the docs, there are a few occasions where in-line code elements containing backticks are fenced by too few, leading to erroneous HTML output.

The first (and the one motivating me to file the issue at all) is:

https://github.com/fredrikekre/DocumenterCodeBlocks.jl/blob/af95de3842781c8216bccd1605a467d03b2933a1/docs/src/linenumbers.md?plain=1#L98

(that also exists in an—invisible—code comment)

https://github.com/fredrikekre/DocumenterCodeBlocks.jl/blob/af95de3842781c8216bccd1605a467d03b2933a1/src/pipeline.jl#L131

Julia's Markdown parser (unlike GFM) treats an even number of backticks as LaTeX code, and thus Documenter outputs it as $‘‘‘juliatutorial$. The fix is trivial, one just needs to add an additional backtick:

```diff
- ```` ```julia tutorial ````
+ ````` ```julia tutorial `````
```

I found two more occasions with similar issues:

https://github.com/fredrikekre/DocumenterCodeBlocks.jl/blob/af95de3842781c8216bccd1605a467d03b2933a1/docs/src/warnings.md?plain=1#L60

and

https://github.com/fredrikekre/DocumenterCodeBlocks.jl/blob/af95de3842781c8216bccd1605a467d03b2933a1/src/DocumenterCodeBlocks.jl#L66

The fixes are just as simple, triple backticks for the first example:

```diff
- `[`frob(a, b, c, d)`](@ref)`
+ ```[`frob(a, b, c, d)`](@ref)```
```

and fivefold backticks for the second:

```diff
- ` ```julia name `
+ ````` ```julia name `````
```

As "proof", I'll attach a screenshot of the Documenter output:

From my reading of the docs and a quick `grep` over the repo, I assume these are the only occurrences.

Start with the four occurrences linked in docs/src/linenumbers.md, src/pipeline.jl, docs/src/warnings.md, and src/DocumenterCodeBlocks.jl, then use grep to confirm the issue's scan. Adjust each inline-code fence to use enough backticks for its contents, and verify that the affected documentation renders without erroneous HTML output.

Written by the indexing model from the issue text.