Fix README typo (h/t @choiasher) + nix v0.6.0 note

README.md

@@ -23,6 +23,7 @@ Currently [tested](tests/) on [Python 2.7, 3.1, 3.4, 3.5, and 3.6](tox.ini).
 ```sh
 pip install pdfplumber
 ```
+
 ## Command line interface
 
 ### Basic example
@@ -304,7 +305,7 @@ By default, `extract_tables` uses the page's vertical and horizontal lines (or r
 |`"vertical_strategy"`| Either `"lines"`, `"lines_strict"`, `"text"`, or `"explicit"`. See explanation below.|
 |`"horizontal_strategy"`| Either `"lines"`, `"lines_strict"`, `"text"`, or `"explicit"`. See explanation below.|
 |`"explicit_vertical_lines"`| A list of vertical lines that explicitly demarcate cells in the table. Can be used in combination with any of the strategies above. Items in the list should be either numbers — indicating the `x` coordinate of a line the full height of the page — or a dictionary describing the line, with at least the following keys: `x`, `top`, `bottom`. |
-|`"explicit_horizontal_lines"`| A list of vertical lines that explicitly demarcate cells in the table. Can be used in combination with any of the strategies above. Items in the list should be either numbers — indicating the `y` coordinate of a line the full height of the page — or a dictionary describing the line, with at least the following keys: `top`, `x0`, `x1`.|
+|`"explicit_horizontal_lines"`| A list of horizontal lines that explicitly demarcate cells in the table. Can be used in combination with any of the strategies above. Items in the list should be either numbers — indicating the `y` coordinate of a line the full height of the page — or a dictionary describing the line, with at least the following keys: `top`, `x0`, `x1`.|
 |`"snap_tolerance"`| Parallel lines within `snap_tolerance` pixels will be "snapped" to the same horizontal or vertical position.|
 |`"join_tolerance"`| Line segments on the same infinite line, and whose ends are within `join_tolerance` of one another, will be "joined" into a single line segment.|
 |`"edge_min_length"`| Edges shorter than `edge_min_length` will be discarded before attempting to reconstruct the table.|
@@ -377,4 +378,4 @@ Many thanks to the following users who've contributed ideas, features, and fixes
 
 ## Contributing
 
-Pull requests are welcome, but please submit an issue (or email [email protected]) before submitting one, as the library is in active development. The current development branch is `v0.6.0`.
+Pull requests are welcome, but please submit an issue (or email [email protected]) before submitting one, as the library is in active development.