`<stacktrace>`: document limits

<stacktrace> has the following limitations:

• The stack capturing is done using CaptureStackBackTrace function. As a result:
  • The skip parameter in basic_stacktrace::current is limited to at most 0xFFFF'FFFF (the actual limit might be lower).
  • The max_depth parameter in basic_stacktrace::current is limited to 0xFFFF - see #2776.
  • Only non-inlined function addressees are captured. Inline stack frames and parameter values are not captured. (inline and __forceinline keywords do not imply the function is inlined, and the absence of these keywords does not imply that the function is not inlined).
  • It does not work under ARM64 for x64 binaries (returns empty traces)
• The symbols resolution is done lazily, as intended by the Standard. It means that if stack trace contains pointers to a DLL that has already been unloaded, it may not resolve correctly.
• The symbols resolution uses DbgEng from within the current process. Consequently:
  • The symbol resolution relies on .pdbs availability. As an alternative, export names are used. If neither is present, module names and offsets are used.
  • There are likely some issues with the concurrent use of DbgHelp and potentially with the concurrent use of DbgEng library.
  • If .exe and .pdb are moved to another folder name from the one where theyy were created during build, the .pdb will not get picked by default. Use /PDBALTPATH:%_PDB% to work around this limitation.
• There's no control over various options for DbgEng
• There's no control on whether network / Internet symbols are used. DbgEng uses _NT_SYMBOL_PATH as usual. (Set _NT_SYMBOL_PATH via _putenv, _wputenv or SetEnvironmentVariable prior to the first use of <stacktrace> to control locations of symbols)
• Overall, the facility has limited usage in the case of fatal errors, where the state of process is corrupted. Usually, such errors cannot be handled in a reliable and meaningful way from the current process. Use error handling that relies on external process or service instead, such as Windows Error Reporting

Start with the documentation and the basic_stacktrace::current entry point; the issue does not name a documentation file or test. Incorporate the listed CaptureStackBackTrace, DbgEng, symbol-resolution, and fatal-error limitations, then verify that the published documentation covers each limitation accurately.