Fixes grammar and typos in Javadoc

[mawiesne]

• fixes grammar issues in JavaDoc and code comments.
• fixes some typos found along the way.
• improves JavaDoc, highlighting the keywords: null, true, false.

[codecov-commenter]

Codecov Report

Merging #233 (3422e3e) into master (e0d6fe0) will increase coverage by 0.38%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #233      +/-   ##
============================================
+ Coverage     74.65%   75.04%   +0.38%     
- Complexity      445      448       +3     
============================================
  Files            38       38              
  Lines          1823     1823              
  Branches        181      181              
============================================
+ Hits           1361     1368       +7     
+ Misses          348      341       -7     
  Partials        114      114              

Impacted Files	Coverage Δ
...rc/main/java/org/apache/commons/crypto/Crypto.java	80.48% <ø> (ø)
...va/org/apache/commons/crypto/NativeCodeLoader.java	50.00% <ø> (ø)
...rc/main/java/org/apache/commons/crypto/OsInfo.java	66.12% <ø> (ø)
...org/apache/commons/crypto/cipher/CryptoCipher.java	100.00% <ø> (ø)
...va/org/apache/commons/crypto/cipher/JceCipher.java	75.00% <ø> (ø)
...java/org/apache/commons/crypto/cipher/OpenSsl.java	80.48% <ø> (ø)
...rg/apache/commons/crypto/cipher/OpenSslCipher.java	75.60% <ø> (ø)
...ommons/crypto/cipher/OpenSslGaloisCounterMode.java	66.66% <ø> (ø)
...java/org/apache/commons/crypto/jna/OpenSslJna.java	60.00% <ø> (ø)
...rg/apache/commons/crypto/jna/OpenSslJnaCipher.java	80.24% <ø> (+3.70%)	⬆️
... and 6 more

... and 2 files with indirect coverage changes

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[mawiesne]

ping @kinow & @garydgregory