Protect <> in examples

[mglisse]

https://www.boost.org/doc/libs/1_70_0/libs/graph/doc/incremental_components.html
The first example, from examples/incremental_components.cpp, was copy-pasted raw, without protecting special characters from HTML, so in particular all templates are invisible.

[anadon]

I'll queue this up for documentation fixes after I'm done with CI.

[andreacassioli]

To me looks fine, but I see that most of the other algorithm documentations only have a link to the example. Maybe that is the easiest fix.

[Becheler]

Hi people !

• The pointed example file compiles : https://godbolt.org/z/x3bhfzxEP
• The inlined code in the documentation indeed hides the < and > symbols:

instead of

  typedef adjacency_list <vecS, vecS, undirectedS> Graph;
  typedef graph_traits<Graph>::vertex_descriptor Vertex;
  typedef graph_traits<Graph>::vertices_size_type VertexIndex;

This is a well know pain point of inlining C++ code in raw html.

The #491 PR solves this by ditching .html files for adoc and switching to Antora.
When #491 will be merged, I will closed this issue.

Thank you for signaling it! 🎉