Update INSTALL.md

Adjust heading sizes to split the INSTALL.md into smaller sections.

Author: SufianBabri

INSTALL.md

@@ -1,16 +1,16 @@
-## Installing Arc from the source
+# Installing Arc from the source
 
-#### Getting the source
+## Getting the source
 
 To get the source, either clone the git repository with e.g.
 
     git clone https://github.com/jnsh/arc-theme --depth 1
 
 Or download and extract a [snapshot](https://github.com/jnsh/arc-theme/archive/master.zip) of the master git branch, or the latest [release tarball](https://github.com/jnsh/arc-theme/releases/latest).
 
-#### Dependencies
+## Dependencies
 
-##### Build dependencies
+#### Build dependencies
 
 To build the theme the following packages are required:
 * `meson`
@@ -21,7 +21,7 @@ The following packages are only required for building certain themes:
 
 You can avoid these dependencies by choosing to not build specific themes using the `themes` build option.
 
-##### Runtime dependencies
+#### Runtime dependencies
 
 For the GTK 2 theme to function properly, install the following:
 * `gnome-themes-extra`, or `gnome-themes-standard` before GNOME version 3.28
@@ -32,13 +32,13 @@ For the GTK 2 theme to function properly, install the following:
   * `gtk2-engine-murrine` (openSUSE)
   * `gtk-engines-murrine` (Gentoo)
 
-#### Building and installation
+## Building and installation
 
 Arc-theme uses [Meson](https://mesonbuild.com/) build system, refer to its documentation for further information about the build process.
 
 The following instructions should work for most common cases.
 
-##### Setup and configure a build directory
+#### Setup and configure a build directory
 
 First you need to setup and configure a new build directory (e.g. `build/`) from the cloned/extracted source code directory.
 
@@ -52,13 +52,13 @@ The build options can later be changed with `meson configure` command, e.g.
 
     meson configure --prefix=/usr -Dvariants=light,darker build/
 
-##### Build and install
+#### Build and install
 
 Build and install the theme according to your configuration by running the following:
 
     meson install -C build/
 
-##### Note about installation in user's home directory
+#### Note about installation in user's home directory
 
 Some themes (at least GTK 2) aren't loaded from `~/.local/share/themes/`. You can work around this e.g. by symlinking the Arc theme directories in `~/.local/share/themes/` to `~/.themes/` with following commands:
 
@@ -67,7 +67,7 @@ Some themes (at least GTK 2) aren't loaded from `~/.local/share/themes/`. You ca
       [ -d ~/.local/share/themes/$d ] && ln -s ~/.local/share/themes/$d ~/.themes/;
     done
 
-#### Versioned themes
+## Versioned themes
 
 The source code comes branched for different versions of GTK 3, GNOME Shell, and Cinnamon. Only one version of those themes will be built and installed, and using the wrong versions will likely result in visual issues.
 
@@ -80,7 +80,7 @@ Otherwise the build system tries to determine correct versions using the followi
 
 **Note:** The build setup for GTK 3, Cinnamon and GNOME Shell themes will fail, if their versions can't be determined either from the build options, or from installed packages.
 
-#### Build options
+## Build options
 
 Arc-theme specific build options can be set or changed with `meson configure -Doption=value <build_directory>` e.g.
 
@@ -96,7 +96,7 @@ Option | Default value | Description
 `gtk3_version` | - | Build GTK 3 theme for specific version
 `gnome_shell_gresource` | `false` | Compile GNOME Shell theme into a gresource file
 
-#### Uninstallation
+## Uninstallation
 
 Manually remove the theme directories from your install location, e.g.