fix self.client call in code examples

[cyberw]

Solves #946

[codecov]

Codecov Report

Merging #1123 into master will increase coverage by 0.68%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1123      +/-   ##
==========================================
+ Coverage   73.44%   74.13%   +0.68%     
==========================================
  Files          18       18              
  Lines        1736     1782      +46     
  Branches      264      264              
==========================================
+ Hits         1275     1321      +46     
  Misses        399      399              
  Partials       62       62

Impacted Files	Coverage Δ
locust/rpc/zmqrpc.py	100% <0%> (ø)	⬆️
locust/rpc/protocol.py	100% <0%> (ø)	⬆️
locust/contrib/fasthttp.py	91.76% <0%> (+0.14%)	⬆️
locust/core.py	86.16% <0%> (+0.31%)	⬆️
locust/stats.py	82.04% <0%> (+0.64%)	⬆️
locust/runners.py	59.49% <0%> (+1.04%)	⬆️
locust/web.py	81.96% <0%> (+1.61%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 99397dc...a033bf1. Read the comment docs.