Update the JupyterLab version in the docs

Author: krassowski

docs/Installation.ipynb

@@ -28,7 +28,7 @@
     "- runs in your browser, as an extension to JupyterLab\n",
     "- to install it, you need:\n",
     "  - `nodejs >8`\n",
-    "  - `jupyterlab >=1.1,<2`\n",
+    "  - `jupyterlab >=2.1,<3`\n",
     "\n",
     "#### Language Servers\n",
     "\n",
@@ -55,7 +55,7 @@
     "#### conda (minimal python)\n",
     "\n",
     "```bash\n",
-    "conda create -c conda-forge -n lsp 'python >=3.7,<3.8' 'jupyterlab=1.2' 'nodejs>8' python-language-server\n",
+    "conda create -c conda-forge -n lsp 'python >=3.7,<3.8' 'jupyterlab=2.1' 'nodejs>8' python-language-server\n",
     "# Also consider: r-languageserver [*]\n",
     "source activate lsp\n",
     "python -m pip install 'jupyter-lsp=0.8.0' --no-deps\n",
@@ -95,7 +95,7 @@
     "\n",
     "RUN conda install --quiet --yes --freeze-installed \\\n",
     "    'python-language-server' \\\n",
-    "    'jupyterlab=2' \\\n",
+    "    'jupyterlab=2.1' \\\n",
     "    'r-languageserver' \\\n",
     "  && python3 -m pip install --no-cache-dir --no-deps \\\n",
     "    'jupyter-lsp=0.8.0' \\\n",