Merge pull request #14119 from moxiegirl/fix-heading-blanks

Fix heading blanks

docs/installation/ubuntulinux.md

@@ -21,7 +21,7 @@ installation mechanisms. Using these packages ensures you get the latest release
 of Docker. If you wish to install using Ubuntu-managed packages, consult your
 Ubuntu documentation.
 
-##Prerequisites
+## Prerequisites
 
 Docker requires a 64-bit installation regardless of your Ubuntu version.
 Additionally, your kernel must be 3.10 at minimum. The latest 3.10 minor version
@@ -41,11 +41,11 @@ your kernel version:
 >run Docker, see the prerequisites on this page that apply to your Ubuntu
 >version.
 
-###For Trusty 14.04
+### For Trusty 14.04
 
 There are no prerequisites for this version.
 
-###For Precise 12.04 (LTS)
+### For Precise 12.04 (LTS)
 
 For Ubuntu Precise, Docker requires the 3.13 kernel version. If your kernel
 version is older than 3.13, you must upgrade it. Refer to this table to see
@@ -93,12 +93,12 @@ To upgrade your kernel and install the additional packages, do the following:
 5. After your system reboots, go ahead and [install Docker](#installing-docker-on-ubuntu).
 
 
-###For Saucy 13.10 (64 bit)
+### For Saucy 13.10 (64 bit)
 
 Docker uses AUFS as the default storage backend. If you don't have this
 prerequisite installed, Docker's installation process adds it.
 
-##Installation
+## Installation
 
 Make sure you have installed the prerequisites for your Ubuntu version. Then,
 install Docker using the following:

docs/introduction/understanding-docker.md

@@ -123,14 +123,14 @@ images for your use. These can be images you create yourself or you
 can use images that others have previously created. Docker registries are the 
 **distribution** component of Docker.
 
-####Docker containers
+#### Docker containers
 Docker containers are similar to a directory. A Docker container holds everything that
 is needed for an application to run. Each container is created from a Docker
 image. Docker containers can be run, started, stopped, moved, and deleted. Each
 container is an isolated and secure application platform. Docker containers are the
  **run** component of Docker.
 
-##So how does Docker work? 
+## So how does Docker work? 
 So far, we've learned that:
 
 1. You can build Docker images that hold your applications.