minor changes on docs

README.md

@@ -49,15 +49,15 @@ To test if `mrf` is installed successfully, import `mrf` in Python:
 
 ```python
 import mrf, os
-print(os.path.isfile(mrf.__path__[0] + 'iraf/macosx/x_images.e'))
+print(os.path.isfile(os.path.join(mrf.__path__[0], 'iraf/macosx/x_images.e')))
 ```
 `True` means you have installed `mrf` successfully! Bravo!
 
 `Python>=3` is needed, but you can try whether `mrf` still works under `python2`. Check out the dependence of `mrf` depends from `requirements.txt`.
 
 Acknowledgement
 ---------------
-Many scripts and snippets are from [`kungpao`](https://github.com/dr-guangtou/kungpao) (written by [Song Huang](http://dr-guangtou.github.io) and [Jiaxuan Li](http://astrojacobli.github.io)). [Johnny Greco](http://johnnygreco.github.io) kindly shared his idea of the code structure. [Roberto Abbraham](http://www.astro.utoronto.ca/~abraham/Web/Welcome.html) found the first few bugs of this package and provided useful solutions. Here we appreciate their help!
+Many scripts and snippets are from [`kungpao`](https://github.com/dr-guangtou/kungpao) (written by [Song Huang](http://dr-guangtou.github.io) and [Jiaxuan Li](http://astrojacobli.github.io)). [Johnny Greco](http://johnnygreco.github.io) kindly shared his idea of the code structure. [Roberto Abraham](http://www.astro.utoronto.ca/~abraham/Web/Welcome.html) found the first few bugs of this package and provided useful solutions. Here we appreciate their help!
 
 Citation
 -------

docs/source/guide/install.rst

@@ -36,7 +36,7 @@ The following snippet checks the availability of some ``iraf`` files. ``True`` m
 .. code-block:: python
 
     import mrf, os
-    print(os.path.isfile(mrf.__path__[0] + 'iraf/macosx/x_images.e'))
+    print(os.path.isfile(os.path.join(mrf.__path__[0], 'iraf/macosx/x_images.e')))
 
 Requirements
 -------------