Add links to the new primitive types exercises!!

Fixes #29, thank you @ruipserra!!

README.md

@@ -38,6 +38,10 @@ If you need more help or would like to compare solutions, you can ask in [#rust-
 
 - ["primitive_types1.rs"](http://play.rust-lang.org/?code=%2F%2F+Fill+in+the+rest+of+the+line+that+has+code+missing%21%0A%2F%2F+No+hints%2C+there%27s+no+tricks%2C+just+get+used+to+typing+these+%3A%29%0A%0Afn+main%28%29+%7B%0A++++%2F%2F+Booleans+%28%60bool%60%29%0A%0A++++let+is_morning+%3D+true%3B%0A++++if+is_morning+%7B%0A++++++++println%21%28%22Good+morning%21%22%29%3B%0A++++%7D%0A%0A++++let+%2F%2F+Finish+the+rest+of+this+line+like+the+example%21+Or+make+it+be+false%21%0A++++if+is_evening+%7B%0A++++++++println%21%28%22Good+evening%21%22%29%3B%0A++++%7D%0A%7D%0A)
 - ["primitive_types2.rs"](http://play.rust-lang.org/?code=%2F%2F+Fill+in+the+rest+of+the+line+that+has+code+missing%21%0A%2F%2F+No+hints%2C+there%27s+no+tricks%2C+just+get+used+to+typing+these+%3A%29%0A%0Afn+main%28%29+%7B%0A++++%2F%2F+Characters+%28%60char%60%29%0A%0A++++let+my_first_initial+%3D+%27C%27%3B%0A++++if+my_first_initial.is_alphabetic%28%29+%7B%0A++++++++println%21%28%22Alphabetical%21%22%29%3B%0A++++%7D+else+if+my_first_initial.is_numeric%28%29+%7B%0A++++++++println%21%28%22Numerical%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Neither+alphabetic+nor+numeric%21%22%29%3B%0A++++%7D%0A%0A++++let+%2F%2F+Finish+this+line+like+the+example%21+What%27s+your+favorite+character%3F%0A++++%2F%2F+Try+a+letter%2C+try+a+number%2C+try+a+special+character%2C+try+a+character%0A++++%2F%2F+from+a+different+language+than+your+own%2C+try+an+emoji%21%0A++++if+your_character.is_alphabetic%28%29+%7B%0A++++++++println%21%28%22Alphabetical%21%22%29%3B%0A++++%7D+else+if+your_character.is_numeric%28%29+%7B%0A++++++++println%21%28%22Numerical%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Neither+alphabetic+nor+numeric%21%22%29%3B%0A++++%7D%0A%7D%0A)
+- ["primitive_types3.rs"](http://play.rust-lang.org/?code=%2F%2F+Create+an+array+with+at+least+100+elements+in+it+where+the+%3F%3F%3F+is.+%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%3F%3F%3F%0A%0A++++if+a.len%28%29+%3E%3D+100+%7B%0A++++++++println%21%28%22Wow%2C+that%27s+a+big+array%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Meh%2C+I+eat+arrays+like+that+for+breakfast.%22%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+There%27s+a+shorthand+to+initialize+Arrays+with+a+certain+size+that+does+not+%0A%2F%2F+require+you+to+type+in+100+items+%28but+you+certainly+can+if+you+want%21%29%0A%2F%2F+Check+out+the+Primitive+Types+-%3E+Arrays+section+of+the+book%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23arrays%0A%2F%2F+Bonus%3A+what+are+some+other+things+you+could+have+that+would+return+true%0A%2F%2F+for+%60a.len%28%29+%3E%3D+100%60%3F%0A)
+- ["primitive_types4.rs"](http://play.rust-lang.org/?code=%2F%2F+Get+a+slice+out+of+Array+a+where+the+%3F%3F%3F+is+so+that+the+%60if%60+statement%0A%2F%2F+returns+true.+Scroll+down+for+hints%21%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%5B1%2C+2%2C+3%2C+4%2C+5%5D%3B%0A%0A++++let+nice_slice+%3D+%3F%3F%3F%0A%0A++++if+nice_slice+%3D%3D+%5B2%2C+3%2C+4%5D+%7B%0A++++++++println%21%28%22Nice+slice%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Not+quite+what+I+was+expecting...+I+see%3A+%7B%3A%3F%7D%22%2C+nice_slice%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Primitive+Types+-%3E+Slices+section+of+the+book%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23slices%0A%2F%2F+and+use+the+starting+and+ending+indices+of+the+items+in+the+Array%0A%2F%2F+that+you+want+to+end+up+in+the+slice.%0A%0A%2F%2F+If+you%27re+curious+why+the+right+hand+of+the+%60%3D%3D%60+comparison+does+not%0A%2F%2F+have+an+ampersand+for+a+reference+since+the+left+hand+side+is+a%0A%2F%2F+reference%2C+take+a+look+at+the+Deref+coercions+chapter%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fderef-coercions.html%0A)
+- ["primitive_types5.rs"](http://play.rust-lang.org/?code=%2F%2F+Destructure+the+%60cat%60+tuple+so+that+the+println+will+work.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+cat+%3D+%28%22Furry+McFurson%22%2C+3.5%29%3B%0A++++let+%2F*+your+pattern+here+*%2F+%3D+cat%3B%0A%0A++++println%21%28%22%7B%7D+is+%7B%7D+years+old.%22%2C+name%2C+age%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Primitive+Types+-%3E+Tuples+section+of+the+book%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23tuples%0A%2F%2F+Particularly+the+part+about+%22destructuring+lets%22.+You%27ll+need+to%0A%2F%2F+make+a+pattern+to+bind+%60name%60+and+%60age%60+to+the+appropriate+parts%0A%2F%2F+of+the+tuple.+You+can+do+it%21%21%0A)
+- ["primitive_types6.rs"](http://play.rust-lang.org/?code=%2F%2F+Use+a+tuple+index+to+access+the+second+element+of+%60numbers%60.%0A%2F%2F+You+can+put+this+right+into+the+%60println%21%60+where+the+%3F%3F%3F+is.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+numbers+%3D+%281%2C+2%2C+3%29%3B%0A++++println%21%28%22The+second+number+is+%7B%7D%22%2C+%3F%3F%3F%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+While+you+could+use+a+destructuring+%60let%60+for+the+tuple+here%2C+try+%0A%2F%2F+indexing+into+it+instead%2C+as+explained+here%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23tuple-indexing%0A%2F%2F+Now+you+have+another+tool+in+your+toolbox%21%0A)
 
 ### Tests