Updates to FAF Client README

[NicPWNs]

1. First, saw that the YourKit logo was broken, so fixed that.
2. Fixed other grammatical and formatting issues while here.

Please let me know if there's anything else needed for this PR, or if there's any other doc-related items that should be updated here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (61b5567) 58.93% compared to head (d50e140) 58.91%.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #3123      +/-   ##
=============================================
- Coverage      58.93%   58.91%   -0.02%     
+ Complexity      4479     4478       -1     
=============================================
  Files            574      574              
  Lines          20532    20532              
  Branches        1018     1018              
=============================================
- Hits           12100    12096       -4     
- Misses          7897     7901       +4     
  Partials         535      535              

see 2 files with indirect coverage changes

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