docs(tools): add migrate-converged-pkg readme

[Hotell]

Pull request checklist

• Addresses an existing issue: implements partially Implement build infra around TS path aliases for convergence #16889
• Include a change request file using $ yarn change

Description of changes

(give an overview)

Focus areas to test

(optional)

[size-auditor]

Asset size changes

Size Auditor did not detect a change in bundle size for any component!

Baseline commit: f17969bfe99f38432821266657c2664b891ebdc6 (build)

[fabricteam]

Perf Analysis (@fluentui/react)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	840	815	5000
BaseButton	mount	871	898	5000
Breadcrumb	mount	2680	2716	1000
ButtonNext	mount	531	524	5000
Checkbox	mount	1568	1522	5000
CheckboxBase	mount	1289	1293	5000
ChoiceGroup	mount	4819	4762	5000
ComboBox	mount	1005	987	1000
CommandBar	mount	10223	10320	1000
ContextualMenu	mount	6377	6389	1000
DefaultButton	mount	1133	1152	5000
DetailsRow	mount	3640	3779	5000
DetailsRowFast	mount	3804	3813	5000
DetailsRowNoStyles	mount	3530	3557	5000
Dialog	mount	2111	2126	1000
DocumentCardTitle	mount	135	156	1000
Dropdown	mount	3261	3234	5000
FocusTrapZone	mount	1812	1875	5000
FocusZone	mount	1796	1871	5000
IconButton	mount	1727	1731	5000
Label	mount	341	331	5000
Layer	mount	1784	1768	5000
Link	mount	462	453	5000
MakeStyles	mount	1857	1820	50000
MenuButton	mount	1473	1492	5000
MessageBar	mount	2003	2114	5000
Nav	mount	3263	3251	1000
OverflowSet	mount	1033	1045	5000
Panel	mount	1381	2135	1000
Persona	mount	827	826	1000
Pivot	mount	1423	1416	1000
PrimaryButton	mount	1266	1320	5000
Rating	mount	7637	7535	5000
SearchBox	mount	1319	1331	5000
Shimmer	mount	2584	2543	5000
Slider	mount	1948	1971	5000
SpinButton	mount	5025	5069	5000
Spinner	mount	435	427	5000
SplitButton	mount	3170	3167	5000
Stack	mount	516	506	5000
StackWithIntrinsicChildren	mount	1509	1525	5000
StackWithTextChildren	mount	4492	4468	5000
SwatchColorPicker	mount	10285	10097	5000
Tabs	mount	1431	1425	1000
TagPicker	mount	2431	2400	5000
TeachingBubble	mount	11931	11894	5000
Text	mount	433	423	5000
TextField	mount	1391	1423	5000
ThemeProvider	mount	1187	1173	5000
ThemeProvider	virtual-rerender	607	614	5000
ThemeProviderNext	mount	7182	7238	5000
Toggle	mount	830	821	5000
buttonNative	mount	122	102	5000

Perf Analysis (@fluentui/react-northstar)

Perf tests with no regressions

Scenario	Current PR Ticks	Baseline Ticks	Ratio
AttachmentMinimalPerf.default	162	145	1.12:1
TextMinimalPerf.default	374	339	1.1:1
TableMinimalPerf.default	413	386	1.07:1
AnimationMinimalPerf.default	421	398	1.06:1
ButtonMinimalPerf.default	172	163	1.06:1
DividerMinimalPerf.default	370	349	1.06:1
PortalMinimalPerf.default	186	175	1.06:1
BoxMinimalPerf.default	359	343	1.05:1
ChatWithPopoverPerf.default	370	354	1.05:1
HeaderMinimalPerf.default	360	344	1.05:1
LabelMinimalPerf.default	383	369	1.04:1
SegmentMinimalPerf.default	358	345	1.04:1
TextAreaMinimalPerf.default	500	482	1.04:1
FlexMinimalPerf.default	291	283	1.03:1
ListMinimalPerf.default	524	508	1.03:1
ListWith60ListItems.default	655	636	1.03:1
AvatarMinimalPerf.default	202	199	1.02:1
HeaderSlotsPerf.default	778	760	1.02:1
RosterPerf.default	1184	1165	1.02:1
ReactionMinimalPerf.default	382	373	1.02:1
SkeletonMinimalPerf.default	357	350	1.02:1
SplitButtonMinimalPerf.default	3720	3653	1.02:1
TooltipMinimalPerf.default	977	958	1.02:1
CardMinimalPerf.default	539	534	1.01:1
DatepickerMinimalPerf.default	5452	5409	1.01:1
DialogMinimalPerf.default	750	743	1.01:1
ImageMinimalPerf.default	371	368	1.01:1
ListNestedPerf.default	566	559	1.01:1
MenuButtonMinimalPerf.default	1564	1554	1.01:1
PopupMinimalPerf.default	566	559	1.01:1
ProviderMergeThemesPerf.default	1667	1657	1.01:1
RefMinimalPerf.default	241	239	1.01:1
ToolbarMinimalPerf.default	933	920	1.01:1
TreeMinimalPerf.default	782	778	1.01:1
VideoMinimalPerf.default	626	618	1.01:1
AccordionMinimalPerf.default	147	147	1:1
ButtonOverridesMissPerf.default	1666	1661	1:1
ButtonSlotsPerf.default	532	531	1:1
ChatMinimalPerf.default	611	613	1:1
DropdownMinimalPerf.default	3086	3093	1:1
EmbedMinimalPerf.default	4123	4118	1:1
InputMinimalPerf.default	1256	1262	1:1
ProviderMinimalPerf.default	955	955	1:1
RadioGroupMinimalPerf.default	449	448	1:1
StatusMinimalPerf.default	678	675	1:1
IconMinimalPerf.default	625	628	1:1
CustomToolbarPrototype.default	3776	3768	1:1
AttachmentSlotsPerf.default	1148	1156	0.99:1
ChatDuplicateMessagesPerf.default	286	288	0.99:1
LayoutMinimalPerf.default	363	366	0.99:1
LoaderMinimalPerf.default	686	696	0.99:1
SliderMinimalPerf.default	1529	1549	0.99:1
TableManyItemsPerf.default	1910	1925	0.99:1
TreeWith60ListItems.default	166	167	0.99:1
CheckboxMinimalPerf.default	2722	2770	0.98:1
DropdownManyItemsPerf.default	690	707	0.98:1
FormMinimalPerf.default	400	409	0.98:1
ItemLayoutMinimalPerf.default	1224	1244	0.98:1
MenuMinimalPerf.default	827	841	0.98:1
GridMinimalPerf.default	336	346	0.97:1
ListCommonPerf.default	612	631	0.97:1
AlertMinimalPerf.default	274	285	0.96:1
CarouselMinimalPerf.default	443	461	0.96:1