build instructions need reworking about prometheus-cpp

[jupp0r]

Sorry the instructions are outdated. bazel build //:prometheus-cpp works, you could also use cmake. I'll update the readme asap.

[marcpawl]

The new bazel command builds, but seems to deletes the generated library

____[268 / 286] Executing genrule @protobuf//:generate_js_well_known_types_embed [for host]
____[272 / 286] Compiling lib/text_serializer.cc
____Building complete.
Target //:prometheus-cpp up-to-date:
bazel-bin/libprometheus-cpp.a
____Elapsed time: 138.765s, Critical Path: 106.79s

Output from find is:
/build/prometheus-cpp-master/bazel-testlogs
/build/prometheus-cpp-master/bazel-genfiles
/build/prometheus-cpp-master/bazel-out
/build/prometheus-cpp-master/bazel-prometheus-cpp-master
/build/prometheus-cpp-master/bazel-bin
~

[jupp0r]

libprometheus-cpp.a should be in bazel-bin:

$ bazel build //:prometheus-cpp 
..............
INFO: Found 1 target...
Target //:prometheus-cpp up-to-date:
  bazel-bin/libprometheus-cpp.a
INFO: Elapsed time: 2.354s, Critical Path: 0.36s
$ ls bazel-bin
_objs               _virtual_includes   external            libprometheus-cpp.a tests