Update wording in annotations array section, added latex build artefa…

…cts to .gitignore removed unused packages (#320)

* updated wording an annotations array

* Add new latex build artefacts to .gitignore

* Remove unused import in docs-generator.py

.gitignore

@@ -4,6 +4,8 @@ sigmf-spec.pdf
 sigmf-spec.out
 sigmf-spec.log
 sigmf-spec.aux
+sigmf-spec.fls
+sigmf-spec.fdb_latexmk
 svg-inkscape/
 sigmf-spec.html
 main.css

docs-generator.py

@@ -1,6 +1,5 @@
 import json
 import subprocess
-import time
 
 from pylatex import (Command, Document, Figure, Package, Section, Subsection,
                      Subsubsection, Tabular)

sigmf-schema.json

@@ -209,7 +209,7 @@
     },
     "annotations": {
       "default": [],
-      "description": "The `annotations` value is an array of annotation segment objects that describe anything regarding the signal data not part of the Captures and Global objects. It MUST be sorted by the value of each Annotation Segment's `core:sample_start` key, ascending.  Annotation segment Objects contain key/value pairs and MUST contain a `core:sample_start` key/value pair, which indicates the first index  at which the rest of the Segment's key/value pairs apply.  There is no limit to the number of annotations that can apply to the same group of samples. If two annotations have the same `sample_start`, there is no defined ordering between them. If `sample_count` is not provided, it SHOULD be assumed that the annotation applies from `sample_start` through the end of the Dataset, in all other cases `sample_count` MUST be provided. ",
+      "description": "The `annotations` value is an array of annotation segment objects that describe anything regarding the signal data not part of the Captures and Global objects. It MUST be sorted by the value of each Annotation Segment's `core:sample_start` key, ascending.  Annotation segment Objects contain key/value pairs and MUST contain a `core:sample_start` key/value pair, which indicates the first index  at which the rest of the Segment's key/value pairs apply.  There is no limit to the number of annotations that can apply to the same group of samples. If two annotations have the same `sample_start`, there is no defined ordering between them. If two annotations have the same `sample_start`, there is no defined ordering between them. If `sample_count` is not provided, it SHOULD be assumed that the annotation applies from `sample_start` through the end of the corresponding capture, in all other cases `sample_count` MUST be provided. ",
       "type": "array",
       "additionalItems": true,
       "items": {