Add Italian language substitutions

[TomOne]

Substitutions:

• & -> e (https://dictionary.cambridge.org/dictionary/english-italian/and)
• @ -> chiocciola (https://dictionary.cambridge.org/dictionary/english-italian/at-sign)

[codecov]

Codecov Report

Merging #68 (f1df8b6) into master (f347b0c) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #68   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          135       141    +6     
=========================================
+ Hits           135       141    +6     

Impacted Files	Coverage Δ
languages_substitution.go	100.00% <100.00%> (ø)
slug.go	100.00% <100.00%> (ø)