Comment about python version requirements for pattern package (#1011)

* Correcting docs/notebooks/datasets/mycorpus.txt

* Comment about python version requirements

Pattern package which is used in this ipynb is written for Python 2.5+
and has no support for Python 3 yet. Now this is explicitly written in
requirements ipynb section.

* Comment about python version requirement for package pattern

Pattern package which is used in this ipynb is written for Python 2.5+
and has no support for Python 3 yet. Now this is explicitly written in
requirements ipynb section.

docs/notebooks/gensim_news_classification.ipynb

@@ -22,7 +22,7 @@
     "Following are the dependencies for this tutorial:\n",
     "    - Gensim Version >=0.13.1 would be preferred since we will be using topic coherence metrics extensively here.\n",
     "    - matplotlib\n",
-    "    - Patterns library; Gensim uses this for lemmatization.\n",
+    "    - Patterns library; Gensim uses this for lemmatization. ONLY FOR PYTHON 2.5+ - no support for Python 3 yet.\n",
     "    - nltk.stopwords\n",
     "    - pyLDAVis\n",
     "We will be playing around with 4 different topic models here:\n",
@@ -38,7 +38,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": null,
    "metadata": {
     "collapsed": false,
     "nbpresent": {
@@ -1728,7 +1728,7 @@
  "metadata": {
   "anaconda-cloud": {},
   "kernelspec": {
-   "display_name": "Python [default]",
+   "display_name": "Python 2",
    "language": "python",
    "name": "python2"
   },