adds compound definition to glossary

glossary.md

@@ -5,6 +5,7 @@
 * Sample: what is being produced by a deposition. A sample is made up of different stacked layers of material (target) deposited upon another material (substrate).
 * Target: material "consumed" during the deposition.
 * Substrate: material on which the target is deposited.
+* Compound: which material is a target or a substrate made of; substrates of the same batch are made of the same compound.
 * Layer: one of the layers of material of which a sample is composed; every layer can have different properties, both in the physical sense (i.e. shape, thickness...) and regarding their manufacturing process (i.e. frequency of pulses, deposition temperature and pressure...).
 
 ## eLabFTW glossary
@@ -19,7 +20,7 @@
 * JSON: fancy dictionaries with important data.
 
 ### Endpoints
-Base url: https://{ELAB_BASE_URL}:{PORT}/api/v2
+API URL: `https://{ELAB_BASE_URL}:{PORT}/api/v2`
 
 #### GET, PATCH, DELETE
 * `/items/{elabid}`: data on a resource identified by its elabid.