update project documentation

[goatshriek]

Update build and contribution documentation to address any problems noted in #52.

[codecov]

Codecov Report

Merging #58 into master will increase coverage by 0.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #58      +/-   ##
==========================================
+ Coverage   92.43%   92.68%   +0.25%     
==========================================
  Files          20       20              
  Lines        1533     1613      +80     
==========================================
+ Hits         1417     1495      +78     
- Misses        116      118       +2

Impacted Files	Coverage Δ
src/target.c	96.53% <0%> (-0.53%)	⬇️
src/entry.c	92.57% <0%> (+0.26%)	⬆️
src/target/socket.c	95.65% <0%> (+0.35%)	⬆️
src/config/have_sys_socket.c	96.2% <0%> (+0.36%)	⬆️
src/target/network.c	94.64% <0%> (+0.4%)	⬆️
src/target/file.c	89.28% <0%> (+0.6%)	⬆️
src/target/buffer.c	87.5% <0%> (+1.22%)	⬆️
src/target/stream.c	91.52% <0%> (+1.52%)	⬆️

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