Update README and codeowner for parse time op (#552)

Author: helinwang

.github/CODEOWNERS

@@ -17,7 +17,7 @@
 
 /tensorflow_addons/custom_ops/image/ @windqaq @facaiy
 /tensorflow_addons/custom_ops/seq2seq/ @qlzh727
-/tensorflow_addons/custom_ops/text/ @seanpmorgan @facaiy
+/tensorflow_addons/custom_ops/text/ @seanpmorgan @facaiy @helinwang
 
 # Submodule Owners
 # These may not automatically trigger a review because submodule owners do not
@@ -32,3 +32,4 @@
 /tensorflow_addons/layers/sparsemax*.py @AndreasMadsen
 /tensorflow_addons/losses/contrastive*.py @WindQAQ
 /tensorflow_addons/losses/sparsemax*.py @AndreasMadsen
+/tensorflow_addons/text/parse_time*.py @helinwang

tensorflow_addons/text/README.md

@@ -5,12 +5,14 @@
 |:---------- |:----------- |:------------- |
 | skip_gram_ops |  |  |
 | crf | Dheeraj R. Reddy | dheeraj98reddy@gmail.com |
+| parse_time_op | Helin Wang | helin@google.com |
 
 ## Components 
 | Submodule  | Text Processing Function |  Reference  |
 |:---------- |:----------- |:----------- |
 | skip_gram_ops |  skip_gram_sample | https://arxiv.org/abs/1301.3781 |
 | skip_gram_ops |  skip_gram_sample_with_text_vocab | https://arxiv.org/abs/1301.3781 |
+| parse_time_op | parse_time ||
 
 ## Contribution Guidelines
 #### Standard API