Updated SNAPTEL.md - added mention about separated snap-cli repo

[IzabellaRaulin]

Summary of changes:

• updated SNAPTEL.md - added mention about separated snap-cli repo

@intelsdi-x/snap-maintainers

[kjlyon]

@IzabellaRaulin , in this PR, can you also address this issue:

In the example section of SNAPTEL.md, when unloading the plugins, there are two typos.

• mock needs to be changed to mock1
• and the second publisher needs to be changed to mock-file

[IzabellaRaulin]

@kjlyon, according:

the second publisher needs to be changed to mock-file

Thanks for catching that. I will change it.

mock needs to be changed to mock1

snap-plugin-collector-mock1 has a name mock and version 1 (the version has never changed because the plugin is used in tests together with snap-plugin-collector-mock2 to check version swapping), so the name="mock" in this case is as expected

[kjlyon]

LGTM