[NFC][intelpt] Improve IntelPT trace bundle documentation

[jj10306]

Summary

Mention that the LLVM/clang triple must be provided if the trace will be
consumed via SBTraceCursor

Test Plan:

[wallace]

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTBundleLoader.cpp

244

something along these lines is more accurate

[jj10306]

Improve docs

[jj10306]

resolve comments

[wallace]

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTBundleLoader.cpp

244

split this into 80-char lines, please :)

[jj10306]

address comments

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTBundleLoader.cpp

244

wonder why git clang-format didn't suggest this?

[wallace]

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTBundleLoader.cpp

244

I think it's because this is a special kind of string that should be taken literal

lldb/source/Plugins/Trace/intel-pt/TraceIntelPTBundleLoader.cpp

"cpuInfo": {
     "model": integer,
     "stepping": integer
   },
   "processes?": [
     {
       "pid": integer,
       "triple"?: string,
           // Optional clang/llvm target triple.
+          // This must be provided if the trace will be created not using the
+          // CLI or on a machine other than where the target was traced.
       "threads": [
           // A list of known threads for the given process. When context switch
           // data is provided, LLDB will automatically create threads for the
           // this process whenever it finds new threads when traversing the
           // context switches, so passing values to this list in this case is
           // optional.
         {
           "tid": integer,