Fix long option format on docs.podman.io

Escape the two dashes, otherwise they are combined into one long dash.
I tested that this change is safe and still renders correctly on github
and with the man pages.

This commit also contains a small change to make it build locally.
Assuming you have the dependencies installed you can do:
```
cd docs
make html
```
Preview the html files in docs/build/html with
`python -m http.server 8000 --directory build/html`.

Fixes containers/podman.io#373

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

1 files changed, 7 insertions, 7 deletions

diff --git a/docs/source/markdown/podman-manifest-annotate.1.md b/docs/source/markdown/podman-manifest-annotate.1.md
index 2126b71ec..70b077e5b 100644
--- a/docs/source/markdown/podman-manifest-annotate.1.md
+++ b/docs/source/markdown/podman-manifest-annotate.1.md
@@ -12,39 +12,39 @@ Adds or updates information about an image included in a manifest list or image
 
 ## OPTIONS
 
-#### **--annotation** *annotation=value*
+#### **\-\-annotation** *annotation=value*
 
 Set an annotation on the entry for the specified image.
 
-#### **--arch**
+#### **\-\-arch**
 
 Override the architecture which the list or index records as a requirement for
 the image.  This is usually automatically retrieved from the image's
 configuration information, so it is rarely necessary to use this option.
 
 
-#### **--features**
+#### **\-\-features**
 
 Specify the features list which the list or index records as requirements for
 the image.  This option is rarely used.
 
-#### **--os**
+#### **\-\-os**
 
 Override the OS which the list or index records as a requirement for the image.
 This is usually automatically retrieved from the image's configuration
 information, so it is rarely necessary to use this option.
 
-#### **--os-features**
+#### **\-\-os-features**
 
 Specify the OS features list which the list or index records as requirements
 for the image.  This option is rarely used.
 
-#### **--os-version**
+#### **\-\-os-version**
 
 Specify the OS version which the list or index records as a requirement for the
 image.  This option is rarely used.
 
-#### **--variant**
+#### **\-\-variant**
 
 Specify the variant which the list or index records for the image.  This option
 is typically used to distinguish between multiple entries which share the same