Create README.md for IsRoBERTa language model (#7640)

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Co-authored-by: Julien Chaumond <chaumond@gmail.com>

model_cards/neurocode/IsRoBERTa/README.md

+---
+language: is
+datasets:
+- Icelandic portion of the OSCAR corpus from INRIA
+- oscar
+---
+
+# IsRoBERTa a RoBERTa-like masked language model
+
+Probably the first icelandic transformer language model!
+
+## Overview
+**Language:** Icelandic  
+**Downstream-task:** masked-lm 
+**Training data:** OSCAR corpus 
+**Code:**  See [here](https://github.com/neurocode-io/icelandic-language-model)
+**Infrastructure**: 1x Nvidia K80
+
+## Hyperparameters
+
+```
+per_device_train_batch_size = 48
+n_epochs = 1
+vocab_size = 52.000
+max_position_embeddings = 514
+num_attention_heads = 12
+num_hidden_layers = 6
+type_vocab_size = 1
+learning_rate=0.00005
+``` 
+
+
+## Usage
+
+### In Transformers
+```python
+from transformers import (
+  pipeline,
+  AutoTokenizer,
+  AutoModelWithLMHead
+)
+
+model_name = "neurocode/IsRoBERTa"
+
+tokenizer = AutoTokenizer.from_pretrained(model_name)
+model = AutoModelWithLMHead.from_pretrained(model_name)
+>>> fill_mask = pipeline(
+...     "fill-mask",
+...     model=model,
+...     tokenizer=tokenizer
+... )
+>>> result = fill_mask("Hann fór út að <mask>.")
+>>> result
+[
+  {'sequence': '<s>Hann fór út að nýju.</s>', 'score': 0.03395755589008331, 'token': 2219, 'token_str': 'Ġnýju'},
+  {'sequence': '<s>Hann fór út að undanförnu.</s>', 'score': 0.029087543487548828, 'token': 7590, 'token_str': 'Ġundanförnu'},
+  {'sequence': '<s>Hann fór út að lokum.</s>', 'score': 0.024420788511633873, 'token': 4384, 'token_str': 'Ġlokum'},
+  {'sequence': '<s>Hann fór út að þessu.</s>', 'score': 0.021231256425380707, 'token': 921, 'token_str': 'Ġþessu'},
+  {'sequence': '<s>Hann fór út að honum.</s>', 'score': 0.0205782949924469, 'token': 1136, 'token_str': 'Ġhonum'}
+]
+```
+
+
+## Authors
+Bobby Donchev: `contact [at] donchev.is`
+Elena Cramer: `elena.cramer [at] neurocode.io`
+
+## About us
+
+We bring AI software for our customers live
+Our focus: AI software development
+ 
+Get in touch:
+[LinkedIn](https://de.linkedin.com/company/neurocodeio) | [Website](https://neurocode.io)