Do not allow to auto-retry a job more than 2 times

doc/ci/yaml/README.md

@@ -1147,7 +1147,7 @@ up to the amount of times specified by the `retry` keyword.
 
 If `retry` is set to 3, and a job succeeds in a second run, it won't be retried
 again. `retry` value has to be a positive integer, equal or larger than 0, but
-lower than 10.
+lower or equal to 2 (two retries maximum, three runs in total).
 
 A simple example:
 

lib/gitlab/ci/config/entry/job.rb

@@ -25,7 +25,7 @@ module Gitlab
               validates :allow_failure, boolean: true
               validates :retry, numericality: { only_integer: true,
                                                 greater_than_or_equal_to: 0,
-                                                less_than: 10 }
+                                                less_than_or_equal_to: 2 }
               validates :when,
                 inclusion: { in: %w[on_success on_failure always manual],
                              message: 'should be on_success, on_failure, ' \

spec/lib/gitlab/ci/config/entry/job_spec.rb

@@ -115,7 +115,7 @@ describe Gitlab::Ci::Config::Entry::Job do
 
           it 'returns error about value too high' do
             expect(entry).not_to be_valid
-            expect(entry.errors).to include 'job retry must be less than 10'
+            expect(entry.errors).to include 'job retry must be less than or equal to 2'
           end
         end
       end