Add documentation on template store

Adding documentation to describe the template store
command which is a feature in the cli version 0.8.1
along with adding description with the two existing
constant which set the default locations for the
template store and the default template URL from which
you pull the templates

Signed-off-by: Martin Dekov (VMware) <[email protected]>

Author: Martin Dekov (VMware)

docs/cli/templates.md

@@ -324,6 +324,54 @@ You can use your own Git repository for a custom or forked set of templates. Thi
 
 See `faas-cli template pull` for more information.
 
+If you want to set up your own default template location, specify the `OPENFAAS_TEMPLATE_URL` environmental variable the following way:
+
+```bash
+export OPENFAAS_TEMPLATE_URL=https://raw.githubusercontent.com/user/mytemplate/customtemplates
+```
+
+#### 8.4 Download templates from the template store
+
+> Note: In order to access the template store you need `0.8.1` version of the CLI or higher
+
+Check what templates are available in the template store with the CLI by typing:
+
+```bash
+faas-cli template store list
+```
+
+Pull the desired template by specifying `NAME` attribute only:
+
+```bash
+faas-cli template store pull go
+```
+
+or pull the template by mixing the `REPOSITORY` and `NAME` attributes the following way:
+
+```bash
+faas-cli template store pull openfaas/go
+```
+
+To get more information on specific store use the `describe` verb like:
+
+```bash
+faas-cli template store describe openfaas/go
+```
+
+or if there is no collision between names use only the name field:
+
+```bash
+faas-cli template store describe go
+```
+
+If you have your own store with templates, you can set that as your default official store by setting the environmental variable `OPENFAAS_TEMPLATE_STORE_URL` the following way:
+
+```bash
+export OPENFAAS_TEMPLATE_STORE_URL=https://raw.githubusercontent.com/user/openfaas-templates/templates.json
+```
+
+Now the source of the store is changed to the URL you have specified above.
+
 ## ARM / Raspberry Pi
 
 Templates for ARM and Raspberry Pi are provided on a best-effort basis. If you can help with maintenance please let the project contributors know.