README.md in sec_id-4.0.0 vs README.md in sec_id-4.1.0

@@ -9,21 +9,23 @@
 Check-digit calculation is also available.
 
 Currently supported standards:
 [ISIN](https://en.wikipedia.org/wiki/International_Securities_Identification_Number),
 [CUSIP](https://en.wikipedia.org/wiki/CUSIP),
-[SEDOL](https://en.wikipedia.org/wiki/SEDOL)
+[SEDOL](https://en.wikipedia.org/wiki/SEDOL),
+[FIGI](https://en.wikipedia.org/wiki/Financial_Instrument_Global_Identifier),
+[CIK](https://en.wikipedia.org/wiki/Central_Index_Key).
 
 Work in progress:
 [IBAN](https://en.wikipedia.org/wiki/International_Bank_Account_Number).
 
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-gem 'sec_id', '~> 4.0'
+gem 'sec_id', '~> 4.1'
 ```
 
 And then execute:
 
     $ bundle
@@ -113,10 +115,11 @@
 isin.check_digit           # => 5
 isin.valid?                # => true
 isin.valid_format?         # => true
 isin.restore!              # => 'US5949181045'
 isin.calculate_check_digit # => 5
+isin.to_cusip              # => #<SecId::CUSIP>
 ```
 
 ### SecId::CUSIP full example
 
 ```ruby
@@ -134,10 +137,12 @@
 cusip.check_digit           # => 4
 cusip.valid?                # => true
 cusip.valid_format?         # => true
 cusip.restore!              # => '594918104'
 cusip.calculate_check_digit # => 4
+cusip.to_isin('US')         # => #<SecId::ISIN>
+cusip.cins?                 # => true
 ```
 
 ### SecId::SEDOL full example
 
 ```ruby
@@ -153,9 +158,51 @@
 cusip.check_digit           # => 5
 cusip.valid?                # => true
 cusip.valid_format?         # => true
 cusip.restore!              # => 'B0Z52W5'
 cusip.calculate_check_digit # => 5
+```
+
+### SecId::FIGI full example
+
+```ruby
+# class level
+SecId::FIGI.valid?('BBG000DMBXR2')        # => true
+SecId::FIGI.valid_format?('BBG000DMBXR2') # => true
+SecId::FIGI.restore!('BBG000DMBXR')       # => 'BBG000DMBXR2'
+SecId::FIGI.check_digit('BBG000DMBXR')    # => 2
+
+# instance level
+figi = SecId::FIGI.new('BBG000DMBXR2')
+figi.full_number           # => 'BBG000DMBXR2'
+figi.prefix                # => 'BB'
+figi.random_part           # => '000DMBXR'
+figi.check_digit           # => 2
+figi.valid?                # => true
+figi.valid_format?         # => true
+figi.restore!              # => 'BBG000DMBXR2'
+figi.calculate_check_digit # => 2
+```
+
+### SecId::CIK full example
+
+```ruby
+# class level
+SecId::CIK.valid?('0001094517')        # => true
+SecId::CIK.valid_format?('0001094517') # => true
+SecId::CIK.restore!('1094517')         # => '0001094517'
+SecId::CIK.check_digit('0001094517')   # raises NotImplementedError
+
+# instance level
+cik = SecId::CIK.new('0001094517')
+cik.full_number           # => '0001094517'
+cik.padding               # => '000'
+cik.identifier            # => '1094517'
+cik.valid?                # => true
+cik.valid_format?         # => true
+cik.restore!              # => '0001094517'
+cik.calculate_check_digit # raises NotImplementedError
+cik.check_digit           # => nil
 ```
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies.