create "Get Started" vignette

[maelle]

• what is glitter goal (as in README)
• good to know
• Be clearer in docs/vignettes about triplet argument being handled differently #73

@lvaudor let's store ideas here

[lvaudor]

writing a simple query

• show spq_init() + spq_add() + spq_perform(), (on wikidata, on type of object with few occurrences for instance the stations of the Lyon subway network)
• Wikidata url to explore identifiers

labelling

(with an example on Wikidata)

adding triple patterns

• add another triple pattern (for instance geographical coordinates)
• mention .required

detailing queries

with dplyr-like functions (filter, select, mutate, summarise)

querying other triplestores

• show on e.g. dbpedia (example with spq_label())
• mention usual_endpoints
• mention usual_prefixes

[maelle]

wait so no mutate, filter, etc?

[lvaudor]

wait so no mutate, filter, etc?

Si si, I've added them above