Add footer link to repository and add a little more info to about page

[davidwyld]

Resolves #204

[github-actions]

Jest Coverage

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	78.2	76.63	71.66	78.2

Details

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	78.2	76.63	71.66	78.2
_src/components	77.14	77.35	85.71	77.14
_ AnnotationRenderer.vue	76.23	77.35	84	76.23	126,141-142,196,219,240,247-261,269,275-285,319
_ MarkdownEditor.vue	100	100	100	100
_ MarkdownRenderer.vue	100	100	100	100
_src/components/annotation	78.57	86.66	76.47	78.57
_ CheckboxInput.vue	85.71	100	100	85.71	19
_ HtmlDisplay.vue	80	100	100	80	26-30
_ InputErrorDisplay.vue	100	0	100	100	19-25
_ RadioInput.vue	71.42	100	66.66	71.42	19,26
_ SelectorInput.vue	71.42	100	66.66	71.42	20,27
_ TextInput.vue	75	100	66.66	75	26
_ TextareaInput.vue	66.66	100	50	66.66	20
_src/enum	100	100	100	100
_ DocumentTypes.js	100	100	100	100
_src/jrpc	90.32	83.33	75	90.32
_ index.js	90.32	83.33	75	90.32	29,38-39
_src/utils	70.58	69.69	27.27	70.58
_ annotations.js	100	100	100	100
_ dict.js	100	100	100	100
_ index.js	55.88	54.54	11.11	55.88	9-14,28-93
_tests/unit	100	100	100	100
_ globalVue.js	100	100	100	100

[twinkarma]

LGTM!