Fix typos

Found via `codespell`

README.md

@@ -210,7 +210,7 @@ Fugit tries to follow the `man 5 crontab` documentation.
 
 There is a surprising thing about this canon, all the columns are joined by ANDs, except for monthday and weekday which are joined together by OR if they are both set (they are not `*`).
 
-Many people (me included) [are suprised](https://superuser.com/questions/428807/run-a-cron-job-on-the-first-monday-of-every-month) when they try to specify "at 05:00 on the first Monday of the month" as `0 5 1-7 * 1` or `0 5 1-7 * mon` and the results are off.
+Many people (me included) [are surprised](https://superuser.com/questions/428807/run-a-cron-job-on-the-first-monday-of-every-month) when they try to specify "at 05:00 on the first Monday of the month" as `0 5 1-7 * 1` or `0 5 1-7 * mon` and the results are off.
 
 The man page says:
 

spec/cron_spec.rb

@@ -1715,7 +1715,7 @@ class Fugit::Cron::TimeCursor
 
   describe '#within' do
 
-    it 'returns all the occurences within a given time period' do
+    it 'returns all the occurrences within a given time period' do
 
       c = Fugit.parse_cron('0 12 * * mon#2')
 
@@ -1736,7 +1736,7 @@ class Fugit::Cron::TimeCursor
       end
     end
 
-    it 'returns all the occurences within a start time and an end time' do
+    it 'returns all the occurrences within a start time and an end time' do
 
       c = Fugit.parse_cron('0 12 * * mon#2')