Make contributing doc page title shorter

[dstansby]

Should make it look nicer in the doc header - currently it's a bit cramped:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.54%. Comparing base (169517e) to head (7c3ec44).
Report is 44 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (169517e) and HEAD (7c3ec44). Click for more details.

HEAD has 23 uploads less than BASE

Flag	BASE (169517e)	HEAD (7c3ec44)
	24	1

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #634      +/-   ##
==========================================
- Coverage   99.81%   94.54%   -5.28%     
==========================================
  Files          62       62              
  Lines        2712     2712              
==========================================
- Hits         2707     2564     -143     
- Misses          5      148     +143     

see 9 files with indirect coverage changes

[jakirkham]

Less is more :)