Pick up changes from pprof's copy of profile.proto

PiperOrigin-RevId: 669350670

src/profile.proto

@@ -93,11 +93,12 @@ message Profile {
   // Index into the string table of the type of the preferred sample
   // value. If unset, clients should default to the last sample value.
   int64 default_sample_type = 14;
-  // disable-diff-check:begin  -- disabled until proto change is in google3
-  // Documentation link for this profile. May be missing if the profile was
-  // generated by older code or code that did not bother to supply a link.
+  // Documentation link for this profile. The URL must be absolute,
+  // e.g., http://pprof.example.com/cpu-profile.html
+  //
+  // The URL may be missing if the profile was generated by older code or code
+  // that did not bother to supply a link.
   int64 doc_url = 15;  // Index into string table.
-  // disable-diff-check:end
 }
 
 // ValueType describes the semantics and measurement units of a value.